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Image enlargement software



 
 
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  #21  
Old October 16th 14, 03:13 AM posted to rec.photo.digital
Mayayana
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Posts: 1,514
Default 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  
Old October 16th 14, 03:24 AM posted to rec.photo.digital
Eric Stevens
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Posts: 13,611
Default 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  
Old October 16th 14, 03:43 AM posted to rec.photo.digital
Mayayana
external usenet poster
 
Posts: 1,514
Default 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  
Old October 16th 14, 04:19 AM posted to rec.photo.digital
Floyd L. Davidson
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Posts: 5,138
Default 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  
Old October 16th 14, 05:07 AM posted to rec.photo.digital
John McWilliams
external usenet poster
 
Posts: 6,945
Default 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  
Old October 16th 14, 05:09 AM posted to rec.photo.digital
John McWilliams
external usenet poster
 
Posts: 6,945
Default 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  
Old October 16th 14, 05:13 AM posted to rec.photo.digital
Floyd L. Davidson
external usenet poster
 
Posts: 5,138
Default 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  
Old October 16th 14, 05:38 AM posted to rec.photo.digital
Floyd L. Davidson
external usenet poster
 
Posts: 5,138
Default 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  
Old October 16th 14, 06:17 AM posted to rec.photo.digital
John McWilliams
external usenet poster
 
Posts: 6,945
Default 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  
Old October 16th 14, 06:19 AM posted to rec.photo.digital
John McWilliams
external usenet poster
 
Posts: 6,945
Default 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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