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#51
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Lightroom vs Photoshop when printing.
Eric Stevens wrote:
On Sat, 28 Mar 2015 00:28:05 -0800, (Floyd L. Davidson) wrote: --- snip --- If you print... use sRGB and calibrate the monitor at a brightness, gamma and color temperature that is as close as possible to the specific printer. But how can you? Your monitor is an illuminated additive RGB device while a print is a subtractive CMYK device. The closest you can get to what you advocate is soft proofing. Ah, the light went on? It's been on here for some time. It isn't perfect, and what I said was "as close as possible". ... and frankly that is a most peculiar idea which is almsot impossible to realise in practise outside the world of soft proofing. I don't understand your comment. "Soft proofing" is exactly what is done. And if it is otherwise impossible to do, then that is why it is suggested as the thing to do. I guess it depends how the soft-proofing is defined. All of the applications I have (NX2, Photo Paint, Paintshop Pro, DxO, Photoshop, Lightroom) take into account the ICC (colour) profile of the target device (the particular paper in the particular printer). The ICC profile describes the device's colour gamut, the black and white points, and the tonal response. The nearest thing to an ICC profile is your prescription to "If you print... use sRGB ...". The nearest thing to an ICC profile was the comment about adjusting brightness, gamma and color temperature to match the "specific printer". That isn't just the physical printer regardless of the paper, it's the logical printer that includes whatever adjustments are made to the driver (the RIP) and includes the effects of different papers that those adjustments target. 1. It is safe to say that virtually no printer/paper combination has an sRGB profile so there is no way that a screen calibrated to sRGB can simulate it. [Calibrating the screen does not entail calibrating it to any particular colour space, sRGB or otherwise. Calibrating a screen entails discovering what it's particular characteristics may be so that it can properly interpret the output of CMM (colour management engine) of the graphics software.] Calibrating the monitor does specify a color space. What it doesn't specify is the brightness, gamma, and color temperature. It adjusts for variations in the linearity device's actual output. But a "calibrated" monitor can be calibrated for whatever brightness, gamma, and color temperature you choose. 2. The gamma of the target device is described by tonal response data of the device's ICC profile. Gamma is the slope of the brightness curve. You are talking about how closely it matches the response of the device. That's a correction curve. 3. The brightness of the target device is established by the whiteness of the print paper. In fact, it is a misnomer to talk about the brightness of a screen and that of a sheet of paper in the same context. Gamma is gamma, whether a screen or a paper. Same with brightness, though in both cases obviously one is a light source and the other is reflective and therefore depends on the light source used to view it. 4. Printers do not have a colour temperature. The question of colour temperature only arises when interpreting the colours of the original image. Papers have color tint. So do printers and drivers. Your advice at the head of this article is both wrong and unsound in my opinion. Because you aren't necessarily understanding most of the technical aspects, in particular how they relate to each other. -- Floyd L. Davidson http://www.apaflo.com/ Ukpeagvik (Barrow, Alaska) |
#53
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Lightroom vs Photoshop when printing.
Eric Stevens wrote:
On Sat, 28 Mar 2015 15:58:02 -0800, (Floyd L. Davidson) wrote: Eric Stevens wrote: On Sat, 28 Mar 2015 00:28:05 -0800, (Floyd L. Davidson) wrote: --- snip --- If you print... use sRGB and calibrate the monitor at a brightness, gamma and color temperature that is as close as possible to the specific printer. But how can you? Your monitor is an illuminated additive RGB device while a print is a subtractive CMYK device. The closest you can get to what you advocate is soft proofing. Ah, the light went on? It's been on here for some time. It isn't perfect, and what I said was "as close as possible". ... and frankly that is a most peculiar idea which is almsot impossible to realise in practise outside the world of soft proofing. I don't understand your comment. "Soft proofing" is exactly what is done. And if it is otherwise impossible to do, then that is why it is suggested as the thing to do. I guess it depends how the soft-proofing is defined. All of the applications I have (NX2, Photo Paint, Paintshop Pro, DxO, Photoshop, Lightroom) take into account the ICC (colour) profile of the target device (the particular paper in the particular printer). The ICC profile describes the device's colour gamut, the black and white points, and the tonal response. The nearest thing to an ICC profile is your prescription to "If you print... use sRGB ...". The nearest thing to an ICC profile was the comment about adjusting brightness, gamma and color temperature to match the "specific printer". That isn't just the physical printer regardless of the paper, it's the logical printer that includes whatever adjustments are made to the driver (the RIP) and includes the effects of different papers that those adjustments target. You are now talking about a work flow which is very different from the ordinary. It's almost certainly different from the ones used by subscribers to the newsgroup. In fact, it sounds very much like an old fashioned procedure from before the days of colour-managed work flow. Except for a few specialised cases, RIP = Raster Image Processor and is used to convert vector image data into the raster image used by inkjet and laser printers. It's not relevant to the processing of photographic images. Eric... *every* print driver has a RIP internally. You are also talking about a 'logical printer' which is very different from a 'specific printer'. The physical printer is the mechanical device, loaded with a set of inks and a paper. The logical printer is what you get by configuring the device driver. You can, for example, load selectable profiles for half a dozen different papers, which makes each one different. Hence that one physical printer is now half a dozen different logical printers. If you configure an image to be printed it has to match the specific logical printer that it will be sent to. 1. It is safe to say that virtually no printer/paper combination has an sRGB profile so there is no way that a screen calibrated to sRGB can simulate it. [Calibrating the screen does not entail calibrating it to any particular colour space, sRGB or otherwise. Calibrating a screen entails discovering what it's particular characteristics may be so that it can properly interpret the output of CMM (colour management engine) of the graphics software.] Calibrating the monitor does specify a color space. What it doesn't specify is the brightness, gamma, and color temperature. It adjusts for variations in the linearity device's actual output. But a "calibrated" monitor can be calibrated for whatever brightness, gamma, and color temperature you choose. Calibrating a monitor doesn't specify a colour space. It discovers a colour space: the colour space within which the monitor is capable of working. So if a printer can produce 99% of the colors in aRGB any calibration process is going to discover that, and calibrate for aRGB eh? In fact when you set up the calibration device you'll have to tell it which colorspace it is supposed to use. With regard to brightness, gamma and colour temperature, I use the Datapoint Spyder and the first thing it does is measure the ambient light level. Then it specifies the target brightness for the monitor at that light level. When that has been achieved I can carry on and have the monitor calibrated to the generally accepted values of a gamma of 2.2 and a colour temperature of 6500K. Nowhere in the process is any consideration given to to the brightness or colour temperature of the printer, as if printers had these things. Sigh... If it automatically determines the brightness for you based on ambient light, that's wonderful. I don't do that. I tell it what brightness level I want the monitor set for. If you let it automatically choose gamma 2.2 and a temperature of 6500K, good luck to you (that is an abomination in my opinion). It is true that I can nominate a value for the printer's gamma but That isn't the printer's gamma. only if I have the printer do the colour management, which I don't. Having the printer manage the colour is generally not recommended. 2. The gamma of the target device is described by tonal response data of the device's ICC profile. Gamma is the slope of the brightness curve. You are talking about how closely it matches the response of the device. That's a correction curve. Printers and their inks rarely exhibit the classical Gamma curve. It's because they have so many color-dependent kinks and wiggles that their profiles have to make use of Look Up Tables (LUT). That's why I wrote The LUT implements the correction curve. "The gamma of the target device is described by tonal response data of the device's ICC profile". It's not a simple single vaue for gamma. That's the correction, not the gamma. Any way, what is the 'it' that 'matches the response of the device'? Never mind: this getting well away from the subject of proofing an image. 3. The brightness of the target device is established by the whiteness of the print paper. In fact, it is a misnomer to talk about the brightness of a screen and that of a sheet of paper in the same context. Gamma is gamma, whether a screen or a paper. Same with brightness, though in both cases obviously one is a light source and the other is reflective and therefore depends on the light source used to view it. The appearance of a printed image depends on the circumstances under which it is viewed. This affects both the white point and the black point from which the gamma is (in part) derived. 4. Printers do not have a colour temperature. The question of colour temperature only arises when interpreting the colours of the original image. Papers have color tint. So do printers and drivers. That's not the same as colour temperature. Yeah, right. Your advice at the head of this article is both wrong and unsound in my opinion. Because you aren't necessarily understanding most of the technical aspects, in particular how they relate to each other. No wonder this is a mystery to you. -- Floyd L. Davidson http://www.apaflo.com/ Ukpeagvik (Barrow, Alaska) |
#54
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Lightroom vs Photoshop when printing.
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#55
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Lightroom vs Photoshop when printing.
Eric Stevens wrote:
On Sat, 28 Mar 2015 20:28:05 -0800, (Floyd L. Davidson) wrote: --- snip --- Calibrating a monitor doesn't specify a colour space. It discovers a colour space: the colour space within which the monitor is capable of working. So if a printer can produce 99% of the colors in aRGB any calibration process is going to discover that, and calibrate for aRGB eh? Calibration of what? A printer or a monitor? Do you know which one you are talking about? Sorry, the wrong word got typed, which should be clear enough. In fact when you set up the calibration device you'll have to tell it which colorspace it is supposed to use. Nonsense. The "calibration device" has to discover the limits and characteristics of the device being calibrated. How does some other colorspace come into it? You have to compare it to some standard. With regard to brightness, gamma and colour temperature, I use the Datapoint Spyder and the first thing it does is measure the ambient light level. Then it specifies the target brightness for the monitor at that light level. When that has been achieved I can carry on and have the monitor calibrated to the generally accepted values of a gamma of 2.2 and a colour temperature of 6500K. Nowhere in the process is any consideration given to to the brightness or colour temperature of the printer, as if printers had these things. Sigh... If it automatically determines the brightness for you based on ambient light, that's wonderful. I don't do that. I tell it what brightness level I want the monitor set for. Then you have no control over the extent to which your screen image is (or is not) going to be washed out by ambient light. Of course, you could always guess. Do you guess? I tell it what brightness level I want. It's not a guess. If you let it automatically choose gamma 2.2 and a temperature of 6500K, good luck to you (that is an abomination in my opinion). That puts you out on a limb, for a start. Doesn't make sense to you, eh? It is true that I can nominate a value for the printer's gamma but That isn't the printer's gamma. Oh, what is it then? only if I have the printer do the colour management, which I don't. Having the printer manage the colour is generally not recommended. 2. The gamma of the target device is described by tonal response data of the device's ICC profile. Gamma is the slope of the brightness curve. You are talking about how closely it matches the response of the device. That's a correction curve. Printers and their inks rarely exhibit the classical Gamma curve. It's because they have so many color-dependent kinks and wiggles that their profiles have to make use of Look Up Tables (LUT). That's why I wrote The LUT implements the correction curve. The penny has dropped then? "The gamma of the target device is described by tonal response data of the device's ICC profile". It's not a simple single vaue for gamma. That's the correction, not the gamma. The gamma is only an approximation to the required correction. There is nothing magic or fundamental about it, except in mathematical models. Any way, what is the 'it' that 'matches the response of the device'? Never mind: this getting well away from the subject of proofing an image. 3. The brightness of the target device is established by the whiteness of the print paper. In fact, it is a misnomer to talk about the brightness of a screen and that of a sheet of paper in the same context. Gamma is gamma, whether a screen or a paper. Same with brightness, though in both cases obviously one is a light source and the other is reflective and therefore depends on the light source used to view it. The appearance of a printed image depends on the circumstances under which it is viewed. This affects both the white point and the black point from which the gamma is (in part) derived. 4. Printers do not have a colour temperature. The question of colour temperature only arises when interpreting the colours of the original image. Papers have color tint. So do printers and drivers. That's not the same as colour temperature. Yeah, right. Damned right. Your advice at the head of this article is both wrong and unsound in my opinion. Because you aren't necessarily understanding most of the technical aspects, in particular how they relate to each other. No wonder this is a mystery to you. All that is a mystery to me is quite what you are thinking about. I'm going back to 'proofing' an image. You probably shouldn't try discussing this with anyone else either. At least until you study a lot more and find out how the mechanics of it work. And learn what gamma is, not to mention sRGB. -- Floyd L. Davidson http://www.apaflo.com/ Ukpeagvik (Barrow, Alaska) |
#56
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Lightroom vs Photoshop when printing.
On Sun, 29 Mar 2015 00:24:18 -0800, (Floyd L.
Davidson) wrote: Eric Stevens wrote: On Sat, 28 Mar 2015 20:28:05 -0800, (Floyd L. Davidson) wrote: --- snip --- Calibrating a monitor doesn't specify a colour space. It discovers a colour space: the colour space within which the monitor is capable of working. So if a printer can produce 99% of the colors in aRGB any calibration process is going to discover that, and calibrate for aRGB eh? Calibration of what? A printer or a monitor? Do you know which one you are talking about? Sorry, the wrong word got typed, which should be clear enough. It should be, but it isn't. Even on your second try you haven't told us. What are you talking about. In fact when you set up the calibration device you'll have to tell it which colorspace it is supposed to use. Nonsense. The "calibration device" has to discover the limits and characteristics of the device being calibrated. How does some other colorspace come into it? You have to compare it to some standard. You need units of measure. Usually this is one of the CIE varients such as CIELAB, CIEXYZ or similar. These are used to define the various colour spaces such as sRGB, AdobeRGB, Pro PhotoRGB etc. They are also used to define device dependent profiles for monitors, pprinters, scanners, cameras etc. There is no reason why you have to define a colour space before you measure a device dependent profile for the purpose of calibration. With regard to brightness, gamma and colour temperature, I use the Datapoint Spyder and the first thing it does is measure the ambient light level. Then it specifies the target brightness for the monitor at that light level. When that has been achieved I can carry on and have the monitor calibrated to the generally accepted values of a gamma of 2.2 and a colour temperature of 6500K. Nowhere in the process is any consideration given to to the brightness or colour temperature of the printer, as if printers had these things. Sigh... If it automatically determines the brightness for you based on ambient light, that's wonderful. I don't do that. I tell it what brightness level I want the monitor set for. Then you have no control over the extent to which your screen image is (or is not) going to be washed out by ambient light. Of course, you could always guess. Do you guess? I tell it what brightness level I want. It's not a guess. How do you determine the brightness level you want? If you let it automatically choose gamma 2.2 and a temperature of 6500K, good luck to you (that is an abomination in my opinion). That puts you out on a limb, for a start. Doesn't make sense to you, eh? A gamma of 2.2 and a colour temperature of 6500K are virtually industry standards and you usually need some special case before you depart from them. --- long tail of nothing new snipped --- -- Regards, Eric Stevens |
#57
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Lightroom vs Photoshop when printing.
Eric Stevens wrote:
On Sun, 29 Mar 2015 00:24:18 -0800, (Floyd L. Davidson) wrote: Eric Stevens wrote: On Sat, 28 Mar 2015 20:28:05 -0800, (Floyd L. Davidson) wrote: --- snip --- Calibrating a monitor doesn't specify a colour space. It discovers a colour space: the colour space within which the monitor is capable of working. So if a printer can produce 99% of the colors in aRGB any calibration process is going to discover that, and calibrate for aRGB eh? Calibration of what? A printer or a monitor? Do you know which one you are talking about? Sorry, the wrong word got typed, which should be clear enough. It should be, but it isn't. Even on your second try you haven't told us. What are you talking about. "Calibrating a monitor doesn't specify a colour space. It discovers a colour space: the colour space within which the monitor is capable of working." *Is* *not* *correct*. You *specify* the color gamut for *monitor* *calibration*. In fact when you set up the calibration device you'll have to tell it which colorspace it is supposed to use. Nonsense. The "calibration device" has to discover the limits and characteristics of the device being calibrated. How does some other colorspace come into it? You have to compare it to some standard. You need units of measure. Usually this is one of the CIE varients such as CIELAB, CIEXYZ or similar. What are *you* talking about? What "units of measure"? Those describe a color model, they are not a unit of measure. My monitor calibration can use aRGB, sRGB, EBU, REC709, REC1886, REC1885, SMPTE-C, DCI, or it can use the monitor's native color gamut. Of course in practice only aRGB and sRGB are practical options for my use. DCI is "Digital Cinema Standard" and the others are all "Broadcasting" Standards. These are used to define the various colour spaces such as sRGB, AdobeRGB, Pro PhotoRGB etc. They are also used to define device dependent profiles for monitors, pprinters, scanners, cameras etc. There is no reason why you have to define a colour space before you measure a device dependent profile for the purpose of calibration. But when you do calibrate a monitor, you do have to specify what you want. Stop talking in circles. And get a clue about the difference between calibrating a monitor and making a soft profile used by your editing software. With regard to brightness, gamma and colour temperature, I use the Datapoint Spyder and the first thing it does is measure the ambient light level. Then it specifies the target brightness for the monitor at that light level. When that has been achieved I can carry on and have the monitor calibrated to the generally accepted values of a gamma of 2.2 and a colour temperature of 6500K. Nowhere in the process is any consideration given to to the brightness or colour temperature of the printer, as if printers had these things. Sigh... If it automatically determines the brightness for you based on ambient light, that's wonderful. I don't do that. I tell it what brightness level I want the monitor set for. Then you have no control over the extent to which your screen image is (or is not) going to be washed out by ambient light. Of course, you could always guess. Do you guess? I tell it what brightness level I want. It's not a guess. How do you determine the brightness level you want? Same way I determine what speed to drive at, how much to cook dinner, when to get a drink of water, and when to decide Eric is playing games. Experience! I don't set the brightness level to 120 cd/m2. I don't let the calibration software set it either. And while I don't really know, my bet is that you don't do that either! My calibration setup measures ambient light, and tells me what it is, but it does not change anything because of it. If you let it automatically choose gamma 2.2 and a temperature of 6500K, good luck to you (that is an abomination in my opinion). That puts you out on a limb, for a start. Doesn't make sense to you, eh? A gamma of 2.2 and a colour temperature of 6500K are virtually industry standards and you usually need some special case before you depart from them. Industry standard for sRGB as is used on the Internet. Prints are not! Just in case you are interested, my monitor is calibrated at 80 cd/m2, with the color temperature at 5000 K, a gamma of 2.4, and for a color gamut of sRGB. All of those values are entered manually. My calibration absolutely is a little different than yours. I calibrate every two weeks. And you do a software calibration that changes what the video card sends to the monitor, while I do a hardware calibration of the monitor itself, which changes how the monitor displays what comes from the video card. -- Floyd L. Davidson http://www.apaflo.com/ Ukpeagvik (Barrow, Alaska) |
#58
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Lightroom vs Photoshop when printing.
On Sun, 29 Mar 2015 16:34:21 -0800, (Floyd L.
Davidson) wrote: Eric Stevens wrote: On Sun, 29 Mar 2015 00:24:18 -0800, (Floyd L. Davidson) wrote: Eric Stevens wrote: On Sat, 28 Mar 2015 20:28:05 -0800, (Floyd L. Davidson) wrote: --- snip --- Calibrating a monitor doesn't specify a colour space. It discovers a colour space: the colour space within which the monitor is capable of working. So if a printer can produce 99% of the colors in aRGB any calibration process is going to discover that, and calibrate for aRGB eh? Calibration of what? A printer or a monitor? Do you know which one you are talking about? Sorry, the wrong word got typed, which should be clear enough. It should be, but it isn't. Even on your second try you haven't told us. What are you talking about. "Calibrating a monitor doesn't specify a colour space. It discovers a colour space: the colour space within which the monitor is capable of working." *Is* *not* *correct*. You *specify* the color gamut for *monitor* *calibration*. You and I seem to have a fundamental difference of opinion at this point and yours makes no sense to me. In a modern colour managed work flow the gamut of the PCS (Profile Connection Space) is wider than any colour space one is likely to encounter in the real world (other than, possibly, Pro Photo RGB). Before the colour values stored in the PCS can be displayed on the monitor, or printer, or other output device it is necessary to establish the full range of colours that the device can display and the relationship of those colours to the colour values within the colour space. An image within a colour managed work flow will be associated with a particular colour space (This may have been changed from the colour space with which it came in). That colour space will almost certainly be smaller than that of the PCS. The first step of displaying the image is converting it to the colour space associated with the image. The first question which arises is 'can the colour gamut of the converted image fit within the gamut of the monitor?'. If the answer is 'yes', then go ahead and squirt the image on the screen. If the answer is 'no' then we enter a whole new ball game which I have no desire to pursue at the present. Exactly the same situation applies to a printer. Either it can, or cannot, reproduce all the colours that are contained within the image. If it can't, then matters get even more complex than in the case of a screen. Virtually all screens can display the gamut of sRGB. Many have a gamut very close to that of AdobeRGB. Printers are more variable but with the right paper the better printers are very close to AdobeRGB. There are so many variables that it never has been practicable to set up the entire production to match one particular set of circumstances. One does not calibrate a monitor to suit a colour space. One uses the power of the computer to manipulate the image data so that a correctly colored and toned image emerges from the discovered characteristics of the monitor. In fact when you set up the calibration device you'll have to tell it which colorspace it is supposed to use. Nonsense. The "calibration device" has to discover the limits and characteristics of the device being calibrated. How does some other colorspace come into it? You have to compare it to some standard. You need units of measure. Usually this is one of the CIE varients such as CIELAB, CIEXYZ or similar. What are *you* talking about? What "units of measure"? Those describe a color model, they are not a unit of measure. They describe colour models in which (usually) groups of three numerical values are used to describe particular hues and intensities. It is these numerical values which are used to define all the various colour spaces for which you have gone mining (by the way, you missed some :-). My monitor calibration can use aRGB, sRGB, EBU, REC709, REC1886, REC1885, SMPTE-C, DCI, or it can use the monitor's native color gamut. Of course in practice only aRGB and sRGB are practical options for my use. DCI is "Digital Cinema Standard" and the others are all "Broadcasting" Standards. These are used to define the various colour spaces such as sRGB, AdobeRGB, Pro PhotoRGB etc. They are also used to define device dependent profiles for monitors, pprinters, scanners, cameras etc. There is no reason why you have to define a colour space before you measure a device dependent profile for the purpose of calibration. But when you do calibrate a monitor, you do have to specify what you want. So you have to change monitor profiles every time you get an image with a different color space? Stop talking in circles. And get a clue about the difference between calibrating a monitor and making a soft profile used by your editing software. I have a soft profile which is usedy every application on the computer (unless I select a different profile). With regard to brightness, gamma and colour temperature, I use the Datapoint Spyder and the first thing it does is measure the ambient light level. Then it specifies the target brightness for the monitor at that light level. When that has been achieved I can carry on and have the monitor calibrated to the generally accepted values of a gamma of 2.2 and a colour temperature of 6500K. Nowhere in the process is any consideration given to to the brightness or colour temperature of the printer, as if printers had these things. Sigh... If it automatically determines the brightness for you based on ambient light, that's wonderful. I don't do that. I tell it what brightness level I want the monitor set for. Then you have no control over the extent to which your screen image is (or is not) going to be washed out by ambient light. Of course, you could always guess. Do you guess? I tell it what brightness level I want. It's not a guess. How do you determine the brightness level you want? Same way I determine what speed to drive at, how much to cook dinner, when to get a drink of water, and when to decide Eric is playing games. Experience! Another name for guessing. I don't set the brightness level to 120 cd/m2. I don't let the calibration software set it either. And while I don't really know, my bet is that you don't do that either! With my current setup I have set the brightness to 200 cd/m2. If it's not close to that, Spyder will tell me it can't properly calibrate the monitor. My calibration setup measures ambient light, and tells me what it is, but it does not change anything because of it. If you let it automatically choose gamma 2.2 and a temperature of 6500K, good luck to you (that is an abomination in my opinion). That puts you out on a limb, for a start. Doesn't make sense to you, eh? A gamma of 2.2 and a colour temperature of 6500K are virtually industry standards and you usually need some special case before you depart from them. Industry standard for sRGB as is used on the Internet. Prints are not! Hmm. On page 69 of 'The Digital Print' Jeff Schewe writes "I suggest D65 and a gamma of 2.2 ...". On page 133 of the second edition of 'Real World Color Management' Bruce Fraser, Chris Murphy and Fred Bunting write: "For CRT displays the three of us, by separate paths, have come to the same recommended calibration settings: calibrate your monitor to a white point of 6500 K and a gamma of 2.2. You can just take our word for it, but we think it's useful to understand why we like white point-6500 K, and gamma-2.2, so we'll discuss that in the next section. For LCD displays, the only thing you can typically adjust on the monitor itself is the brightness of the backlight. Changes to the color temperature are carried out in the videoLUT, so we recommend using the native white point for LCDs whenever the software allows us to do so. If native white point isn't an option, we use D65 because the color temperature of most LCD backlights is closer to D65 than to anything else." Just in case you are interested, my monitor is calibrated at 80 cd/m2, with the color temperature at 5000 K, a gamma of 2.4, and for a color gamut of sRGB. All of those values are entered manually. My calibration absolutely is a little different than yours. I calibrate every two weeks. And you do a software calibration that changes what the video card sends to the monitor, while I do a hardware calibration of the monitor itself, which changes how the monitor displays what comes from the video card. -- Regards, Eric Stevens |
#59
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Lightroom vs Photoshop when printing.
On Mon, 30 Mar 2015 15:54:23 +1300, Eric Stevens
wrote: Just in case you are interested, my monitor is calibrated at 80 cd/m2, with the color temperature at 5000 K, a gamma of 2.4, and for a color gamut of sRGB. All of those values are entered manually. I meant to add 'You mention nothing which tells you how faithfully the display will reproduce the colour of the image". -- Regards, Eric Stevens |
#60
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Lightroom vs Photoshop when printing.
Eric Stevens wrote:
On Mon, 30 Mar 2015 03:21:29 -0800, (Floyd L. Davidson) wrote: Eric Stevens wrote: On Sun, 29 Mar 2015 22:10:59 -0800, (Floyd L. Davidson) wrote: Eric Stevens wrote: On Sun, 29 Mar 2015 16:34:21 -0800, (Floyd L. Davidson) wrote: Eric Stevens wrote: On Sun, 29 Mar 2015 00:24:18 -0800, (Floyd L. Davidson) wrote: Eric Stevens wrote: On Sat, 28 Mar 2015 20:28:05 -0800, (Floyd L. Davidson) wrote: --- snip --- Calibrating a monitor doesn't specify a colour space. It discovers a Lets not forget that you still haven't admitted how wrong you were on the basis for this entire discussion. Nice diversion. I say " ... then we enter a whole new ball game which I have no desire to pursue at the present." But you then do go right ahead with a diversion trying to find at least something that you can talk about without showing off a how you've said things out of ignorance. .... Now you call my response to you a "Diversion". Because all it amounted to was distancing yourself from admitting that calibrating a monitor requires specifing the color space. It isn't "discovered", it is one of the paramenters the user sets. Exactly the same situation applies to a printer. Either it can, or cannot, reproduce all the colours that are contained within the image. If it can't, then matters get even more complex than in the case of a screen. Actually it is exactly the same problem. Duh! Read the first line of my previous paragraph. And then read how you contradict yourself with that last sentence in the paragraph. There is no contradiction. "Exactly the same" to start with, but "even more complex" when it isn't exactly the same. Yes Eric, that is a contradiction. In fact "aRGB" is a common abbreviation for Adobe RGB (1998). It has nothing to do with 8-bit color. It is a color space. I've never heard or seen of AdobeRGB being referred to in that way before. On the other hand I have heard of aRGB as a reference to a common 8-bit encoding. There is also RGBa which is different. You cannot provide anything that relates it to "common 8-bit encoding", whatever that is supposed to mean. RGBA is indeed something different than aRGB. "DUH!" However, if Google searches on these words: "aRGB" "sRGB" color space it comes up with thousands of examples of using "aRGB" as shorthand for Adobe RGB (1998). Which is not in the slightest new or surprising, considering how much easier it is to type "aRGB" and how similar it is to sRGB. The real problem here is how can you presume to claim any kind of authority on this topic when you are that unfamiliar with it? Stop pronouncing what is, and start asking! It's a misleading misuse of the descriptor. Meaning you just aren't at all well versed on this subject. ... You need units of measure. Usually this is one of the CIE varients such as CIELAB, CIEXYZ or similar. What are *you* talking about? What "units of measure"? Those describe a color model, they are not a unit of measure. They describe colour models in which (usually) groups of three numerical values are used to describe particular hues and intensities. So they are not "units of measure" at all. Of course they a three dimensional coordinates. That is not a unit of measure. Inches, Hertz, gallons and such are units of measure. A ruler is not a unit of measure, and neither is a graduated beaker. Colour spaces are defined numerically. See http://upload.wikimedia.org/wikipedia/commons/thumb/3/3b/CIE1931xy_blank.svg/300px-CIE1931xy_blank.svg.png or http://tinyurl.com/obq6zfz The container is not a "unit of measure". You were just trying to work "buzz words" into your commentary in order to appear as if you knew something. But not knowing what the buzz words actually meant, you used them in a way that very clearly demonstrated how little you understood the topic. It is these numerical values which are used to define all the various colour spaces for which you have gone mining That defines the color space, it is not a unit of measure. It is not a color gamut either, it's a way to define and compare a color gamut within that color space. You are rambling. Precision is just the opposite of rambling. At least we agree on something. So don't you be claiming my precision with terminaology is some form of rambling just because you don't have enough familiarity with the subject to understand. If I do that, why not just say you don't understand and ask for a different description on a lower plane of complexity? When we started this discussion I actually took you at your word on your level of familiarity. Then we go down a list of differences, all the result of non-familiarity, and it seems a simple case that you unnecessarily misrepresented yourself. Everyone with using a managed workflow changes profiles depending on the image and the output device. I don't. Your editing program does, where you realize it or not. Of course I realise that. That's why I don't have to change it myself. So why claim you don't use different profiles when you do! Just trying to be obstinate, and not really understanding the discussion... I've described in detail that it is measured. I'm sorry that went over you head. I tell the calibration program what brightness I want, it measures the output adjusts the brightness control to get that value. This is the first time you have mentioned a calibration program. What do you use? I've mentioned it several times. Obviously I use various programs, none of which you have ever used. It makes no difference what they are as you will not be able to relate the name to anything useful. The way the Spyder 4 (and some other similar devices) operates is, after a sensor is placed on the screen, to run a quick series of both gray scale and color blocks from (0,0,0) to (255,255,255). This enables it to make a quick evaluation of the dynamic range of the monitor. It has already measured the incident light at the work station and from this it is able to calculate the screen brightness required for the proper setting of the white point. There is no guessing, estimation or experience required for the determination of the screen brightness. It is calculated from the measured lighting of the screen and it's environment. The program is taking a guess at what will be appropriate screen brightness for the ambient light level. It might well be more appropriate than what you personally would guess at. The program will match only what the "average" knowledgeable choice would be. For users that need higher or lower brightness that will be the wrong choice. I then have to adjust the on-screen brightness control and have Spyder take a measurement. If the brightness is too high or too low I have to make an adjustment and try again. When it is sufficiently close to the brightness calculated by Spyder it can then proceed with the rest of the calibration procedure. You don't even know what yours is set to, other than whatever the default is! You still haven't been able to specify what it actually is! .... So why not give a value??? It absolutely is not 200 cd/m2! That is only what monitor hardware is set to, and after calibration you video card literally cannot send a signal that will produce anything near that bright! That's the white point! That's one term for it! A good one too. So what is the target "white point" on your monitors when you calibrate them? .... See, you think you are calibrating the monitor to 200 cd/m2, and that is not the case. See above. I most definitely am. Hilarious. You aren't. .... Eizo puts out a nice calibration package, and has an online pdf format user manual ColorNavigator_6_How-to-Use-Guide.pdf that you can download and read. I've just looked at this. The CG series of Eizo monitors have built in sensors. The CX and CS make use of what is clearly a Spyder 4, which is what I use and employs the procedure I have described above. The CG series of Eizo monitors are the ones designed for photography. You still are missing the difference between you using software calibration that sets an LUT for the video card and being able, as the Eizo CG monitors are, to use hardware calibration the set the LUT in the monitor. .... "Compared to software, hardware calibration is much more accurate and there is no need to modify color output through the graphics card." Nasim Mansurov https://photographylife.com/how-to-p...u3014-monitors It is significant. That's interesting. I have a pair of matched (slightly earlier) Dell 2410 monitors. They are calibrated in exactly the same way by Spyder 4 as the article describes the 2413 being matched by the X-Rite. As described by the paragraph '6) Hardware LUT Calibration Process' I have the choice of setting it up to a number color spaces. I use AdobeRGB. That does not mean that it is suited to displaying only AdobeRGB images. It means that images that pass through the monitor's LUT are converted to the AdobeRGB range of colours and gamut. The Dell U2410 is a fairly decent monitor, and a very good value for the money. It does have an internal 12-bit LUT that is used for *factory* calibration to provide gamut emulation. Your calibration software cannot access the monitor's LUT. What you can set is your video card. The cited URL above, if you had read it carefully enough, even specifically says that only the models listed, all high end and newer, are capable of hardware calibration. Who cares whether the calibration is done in the monitor or the video card. The point is the monitors are calibrated. Well, who cares if you don't need accurate repeatable results, that is true. People calibrate laptop monitors too. Is that part of your 'who cares'? It makes a difference. That's why it exists in high end monitors. .... You are not able to read very well. Go back and read it carefully where I said it is calibrated every two weeks. And unlike you, I can actually do a hardware calibration, which everyone says (for good reason) is more accurate. It's more accurate only in the light of a number of assumptions which are not necessarily relevant. Oh, you know better than Dell, NEC or Eizo eh? Name such an assumption and explain how it is not relevant. Sounds like another of your empty headed bits of stubborness in the face of facts that contradict what you've claimed in ignorance and been called on. The fact is you won't find anyone that agrees with you. Worse you will find that every expert on the subject says that hardware calibration is more accurate. -- Floyd L. Davidson http://www.apaflo.com/ Ukpeagvik (Barrow, Alaska) |
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