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#21
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Image enlargement software
| but you can't just take it as a given that in-printer interpolation is
| worse than doing it yourself, Are you sure that printers do resampling? I would have guessed it depends on the software. For instance, if I open an image in even a simple program like IrfanView I can set the print size to whatever is desired. IV also does resampling. Is there any reason to assume that IV and other programs are not doing the resampling themselves before sending it to the printer? I wonder if the printer API even has options for resampling. That's really not part of its job. |
#22
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Image enlargement software
On Wed, 15 Oct 2014 22:13:45 -0400, "Mayayana"
wrote: | but you can't just take it as a given that in-printer interpolation is | worse than doing it yourself, Are you sure that printers do resampling? I would have guessed it depends on the software. For instance, if I open an image in even a simple program like IrfanView I can set the print size to whatever is desired. IV also does resampling. Is there any reason to assume that IV and other programs are not doing the resampling themselves before sending it to the printer? I wonder if the printer API even has options for resampling. That's really not part of its job. You can leave it to the printer driver to resample the image. All you do is feed it a file and tell the printer the desired output size width x breadth. Alternatively you can do as I do: I resample to the size which at 360 ppi will give me the width and breadth that I want. I then tell the printer to print at 100%. That way it does no resampling and outputs the image at the size I want. Of course there are bells and whistles on the printer driver that I may use which can affect the way the printer handles the image, but that's still under my control, not the printer's. -- Regards, Eric Stevens |
#23
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Image enlargement software
| You can leave it to the printer driver to resample the image. All you
| do is feed it a file and tell the printer the desired output size | width x breadth. | Feed it from where? Isn't there some software that's showing you the printer dialog? In my experience that Window is actually just feedback for the software that has an image open. The software then uses your choices to adjust what it sends to the printer. There's usually an option to also open the specific printer settings window, but my printer settings don't include anything like print size. They only include print-specific settings. I've never seen a printer settings dialog that did offer anything like resampling. Unless you're referring to specific high-end printers I think you may be mistaken. |
#24
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Image enlargement software
"Mayayana" wrote:
| You can leave it to the printer driver to resample the image. All you | do is feed it a file and tell the printer the desired output size | width x breadth. | Feed it from where? Isn't there some software that's showing you the printer dialog? In my experience that Window is actually just feedback for the software that has an image open. The software then uses your choices to adjust what it sends to the printer. There's usually an option to also open the specific printer settings window, but my printer settings don't include anything like print size. They only include print-specific settings. I've never seen a printer settings dialog that did offer anything like resampling. Unless you're referring to specific high-end printers I think you may be mistaken. The dialog box is probably part of the print driver, though some programs may usurp part or all of the interface functionality. There is no circumstance where a user actually interfaces directly with the printer to make a print. It always goes through a print driver. Every print driver "offers" resampling. When the user sets a physical size dimension that sets the resampling parameters. If the user then tells the program in use to change the pixel dimensions, that will also change the print driver's resampling. That is because the image file has no physical dimensions, only pixel dimensions. And the printer can only print images at one specific pixel rate. (A given printer might have a "high resolution" mode, but that is for text and line drawings, not photographs. It also may have a draft mode for fast prints, but again that is not for photgraphs. There will be just one PPI rate, e.g. 300 PPI for Canona and HP, and 360 PPI for Epson.) Given that Epson as an example prints at 360 PPI, if the user sets the print driver for a 10 inch wide print, the *only* pixel dimension that can do that is 3600 pixels. If the image being sent to the printer has 1800 pixels across, it *must* be up sampled to 3600. If it has 7200 pixels across it *must* be down sampled to 3600 pixels. That is what the print driver does for you. But, you don't get to see what it looks like before being printed. And it is a simple fact of life that when an image is resampled to a different pixel dimension it needs to be resharpened too, for best results. Down sampling is usually done with an algorithm that has a slight amount of "ringing", which produces a very faint halo. That means less sharpening is needed. If the same algorithm is used for up sampling it will not look good. Instead a filter that has no ringing and might even slight blur edge transitions is best; and that requires a different kind of sharpen than does one that was down sampled. Hence you are far better off to do the size adjustment locally, and the sharpen the results by looking at the effect, before sending an image file to the print driver. -- Floyd L. Davidson http://www.apaflo.com/ Ukpeagvik (Barrow, Alaska) |
#25
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Image enlargement software
On 10/15/14 PDT, 8:19 PM, Floyd L. Davidson wrote:
"Mayayana" wrote: | You can leave it to the printer driver to resample the image. All you | do is feed it a file and tell the printer the desired output size | width x breadth. | Feed it from where? Isn't there some software that's showing you the printer dialog? In my experience that Window is actually just feedback for the software that has an image open. The software then uses your choices to adjust what it sends to the printer. There's usually an option to also open the specific printer settings window, but my printer settings don't include anything like print size. They only include print-specific settings. I've never seen a printer settings dialog that did offer anything like resampling. Unless you're referring to specific high-end printers I think you may be mistaken. The dialog box is probably part of the print driver, though some programs may usurp part or all of the interface functionality. There is no circumstance where a user actually interfaces directly with the printer to make a print. It always goes through a print driver. Every print driver "offers" resampling. When the user sets a physical size dimension that sets the resampling parameters. If the user then tells the program in use to change the pixel dimensions, that will also change the print driver's resampling. That is because the image file has no physical dimensions, only pixel dimensions. And the printer can only print images at one specific pixel rate. (A given printer might have a "high resolution" mode, but that is for text and line drawings, not photographs. It also may have a draft mode for fast prints, but again that is not for photgraphs. There will be just one PPI rate, e.g. 300 PPI for Canona and HP, and 360 PPI for Epson.) Given that Epson as an example prints at 360 PPI, if the user sets the print driver for a 10 inch wide print, the *only* pixel dimension that can do that is 3600 pixels. If the image being sent to the printer has 1800 pixels across, it *must* be up sampled to 3600. If it has 7200 pixels across it *must* be down sampled to 3600 pixels. That is what the print driver does for you. But, you don't get to see what it looks like before being printed. And it is a simple fact of life that when an image is resampled to a different pixel dimension it needs to be resharpened too, for best results. Down sampling is usually done with an algorithm that has a slight amount of "ringing", which produces a very faint halo. That means less sharpening is needed. If the same algorithm is used for up sampling it will not look good. Instead a filter that has no ringing and might even slight blur edge transitions is best; and that requires a different kind of sharpen than does one that was down sampled. Hence you are far better off to do the size adjustment locally, and the sharpen the results by looking at the effect, before sending an image file to the print driver. Good lord, you still cannot fathom the difference between PPI and DPI. |
#26
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Image enlargement software
On 10/15/14 PDT, 3:32 PM, Eric Stevens wrote:
On Wed, 15 Oct 2014 03:02:47 -0400, nospam wrote: In article , Alfred Molon wrote: What's currently the best way to enlarge an image with interpolation? it depends why you're enlarging it and what you want to do with the result. if it's to be printed, let the printer do it. Are there some tools around which are better than others? yes. I've already replied to this but I've finally worked out that when you wrote 'printer' you meant printer as a machine and not as a person. If you are after a high quality print, leaving it to the printer to enlarge the image is definitely not the best way. First, many printer drivers do nothing fancy in the way of pixel interpolation and all you may get is simple pixel interpolation. This is a particularly bad way to handle edges and sharp transitions within the image in that it scales up the softness of the original smaller image. That might not matter when the image is small but it probably will matter when the image is enlarged. Second, once you have fired off an image to the printer to be enlarged you have lost any opportunity to follow the enlargement with further retouching, sharpening etc. It's better to enlarge the image to it's final size in pixels at a relatively early stage in the work flow so that you have a better hope that what you see is what you will get. With most printers this is 300 pixels/dots per inch but Epson use 360 dots/pixels inch. [I expect that at this stage someone will be bursting to have a go at me about the difference between dots and pixels. The distinction is becoming increasingly confused by printers which have a native resolution of (say) 360 print-cells/inch and the ability to print (say) 64 dots, each of a different color, in each print cell. When you add to this the ability of print drivers to mix and match and even change print colors within print cells the connection between print dots and pixels becomes even more tenuous.] Dots and pixels are not the same thing! You and Floyd together. Yeah! |
#27
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Image enlargement software
John McWilliams wrote:
On 10/15/14 PDT, 8:19 PM, Floyd L. Davidson wrote: "Mayayana" wrote: | You can leave it to the printer driver to resample the image. All you | do is feed it a file and tell the printer the desired output size | width x breadth. | Feed it from where? Isn't there some software that's showing you the printer dialog? In my experience that Window is actually just feedback for the software that has an image open. The software then uses your choices to adjust what it sends to the printer. There's usually an option to also open the specific printer settings window, but my printer settings don't include anything like print size. They only include print-specific settings. I've never seen a printer settings dialog that did offer anything like resampling. Unless you're referring to specific high-end printers I think you may be mistaken. The dialog box is probably part of the print driver, though some programs may usurp part or all of the interface functionality. There is no circumstance where a user actually interfaces directly with the printer to make a print. It always goes through a print driver. Every print driver "offers" resampling. When the user sets a physical size dimension that sets the resampling parameters. If the user then tells the program in use to change the pixel dimensions, that will also change the print driver's resampling. That is because the image file has no physical dimensions, only pixel dimensions. And the printer can only print images at one specific pixel rate. (A given printer might have a "high resolution" mode, but that is for text and line drawings, not photographs. It also may have a draft mode for fast prints, but again that is not for photgraphs. There will be just one PPI rate, e.g. 300 PPI for Canona and HP, and 360 PPI for Epson.) Given that Epson as an example prints at 360 PPI, if the user sets the print driver for a 10 inch wide print, the *only* pixel dimension that can do that is 3600 pixels. If the image being sent to the printer has 1800 pixels across, it *must* be up sampled to 3600. If it has 7200 pixels across it *must* be down sampled to 3600 pixels. That is what the print driver does for you. But, you don't get to see what it looks like before being printed. And it is a simple fact of life that when an image is resampled to a different pixel dimension it needs to be resharpened too, for best results. Down sampling is usually done with an algorithm that has a slight amount of "ringing", which produces a very faint halo. That means less sharpening is needed. If the same algorithm is used for up sampling it will not look good. Instead a filter that has no ringing and might even slight blur edge transitions is best; and that requires a different kind of sharpen than does one that was down sampled. Hence you are far better off to do the size adjustment locally, and the sharpen the results by looking at the effect, before sending an image file to the print driver. Good lord, you still cannot fathom the difference between PPI and DPI. That statement applies to you. Everything I said relates to PPI, and I very correctly used PPI rather than DPI. This discussion has very little to do with DPI as opposed to PPI. We are talking pixel rates, not nozzle rates. What part of the difference would you like me to explain to you? -- Floyd L. Davidson http://www.apaflo.com/ Ukpeagvik (Barrow, Alaska) |
#28
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Image enlargement software
John McWilliams wrote:
On 10/15/14 PDT, 3:32 PM, Eric Stevens wrote: On Wed, 15 Oct 2014 03:02:47 -0400, nospam wrote: In article , Alfred Molon wrote: What's currently the best way to enlarge an image with interpolation? it depends why you're enlarging it and what you want to do with the result. if it's to be printed, let the printer do it. Are there some tools around which are better than others? yes. I've already replied to this but I've finally worked out that when you wrote 'printer' you meant printer as a machine and not as a person. If you are after a high quality print, leaving it to the printer to enlarge the image is definitely not the best way. First, many printer drivers do nothing fancy in the way of pixel interpolation and all you may get is simple pixel interpolation. This is a particularly bad way to handle edges and sharp transitions within the image in that it scales up the softness of the original smaller image. That might not matter when the image is small but it probably will matter when the image is enlarged. Second, once you have fired off an image to the printer to be enlarged you have lost any opportunity to follow the enlargement with further retouching, sharpening etc. It's better to enlarge the image to it's final size in pixels at a relatively early stage in the work flow so that you have a better hope that what you see is what you will get. With most printers this is 300 pixels/dots per inch but Epson use 360 dots/pixels inch. [I expect that at this stage someone will be bursting to have a go at me about the difference between dots and pixels. The distinction is becoming increasingly confused by printers which have a native resolution of (say) 360 print-cells/inch and the ability to print (say) 64 dots, each of a different color, in each print cell. When you add to this the ability of print drivers to mix and match and even change print colors within print cells the connection between print dots and pixels becomes even more tenuous.] Dots and pixels are not the same thing! You and Floyd together. Yeah! DPI can mean *exactly* the same thing that PPI does. I tend not to use it that way, but certainly don't get disturbed if others do. Regardless it is pretty clear that Eric understands exactly the difference between a pixel and the multiple nozzle squirts that make a pixel. Think about the "dot clock" in a monitor, think about the DPI setting shown in the Exif data images, and then try your ignorant argument again. Incidentally, DPI was a term that originally meant pixels per inch and each pixel was one dot. -- Floyd L. Davidson http://www.apaflo.com/ Ukpeagvik (Barrow, Alaska) |
#29
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Image enlargement software
On 10/15/14 PDT, 9:13 PM, Floyd L. Davidson wrote:
John McWilliams wrote: Good lord, you still cannot fathom the difference between PPI and DPI. That statement applies to you. Everything I said relates to PPI, and I very correctly used PPI rather than DPI. This discussion has very little to do with DPI as opposed to PPI. We are talking pixel rates, not nozzle rates. What part of the difference would you like me to explain to you? Absolutely, flat out, nothing. Anyone who writes: "Given that Epson as an example prints at 360 PPI, if the user sets the print driver for a 10 inch wide print, the *only* pixel dimension that can do that is 3600 pixels. If the image being sent to the printer has 1800 pixels across, it *must* be up sampled to 3600. If it has 7200 pixels across it *must* be down sampled to 3600 pixels." Doesn't understand. Q.E.D. |
#30
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Image enlargement software
On 10/15/14 PDT, 9:38 PM, Floyd L. Davidson wrote:
John McWilliams wrote: Dots and pixels are not the same thing! You and Floyd together. Yeah! DPI can mean *exactly* the same thing that PPI does. I tend not to use it that way, but certainly don't get disturbed if others do. Regardless it is pretty clear that Eric understands exactly the difference between a pixel and the multiple nozzle squirts that make a pixel. Think about the "dot clock" in a monitor, think about the DPI setting shown in the Exif data images, and then try your ignorant argument again. Incidentally, DPI was a term that originally meant pixels per inch and each pixel was one dot. At one point the two terms were almost interchangeable, but they never truly were the same, but today it's moronic to confuse the two. |
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