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Curves files

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amp photoshop curves Piotr Legiecki 29 Mar 11:37
  amp photoshop curves regis rampnoux 29 Mar 22:57
   amp photoshop curves Austin Donnelly 04 Apr 12:43
    amp photoshop curves Guillermo S. Romero / Familia Romero 04 Apr 17:31
     Curves files regis rampnoux 04 Apr 19:42
      Curves files Guillermo S. Romero / Familia Romero 04 Apr 22:20
       Curves files David Odin 04 Apr 23:09
        Curves files Guillermo S. Romero / Familia Romero 04 Apr 23:14
         Curves files regis rampnoux 05 Apr 00:24
          Curves files Sven Neumann 05 Apr 15:52
  amp photoshop curves Branko Collin 29 Mar 23:10
   amp photoshop curves Robert L Krawitz 30 Mar 00:48
    amp photoshop curves Karl Heinz Kremer 30 Mar 02:06
    amp photoshop curves regis rampnoux 30 Mar 09:08
     amp photoshop curves Robert L Krawitz 30 Mar 14:32
     amp photoshop curves Karl Heinz Kremer 30 Mar 14:50
      amp photoshop curves regis rampnoux 02 Apr 20:51
   amp photoshop curves Nick Lamb 30 Mar 21:48
    amp photoshop curves Nathan C Summers 31 Mar 10:23
     amp photoshop curves Sven Neumann 04 Apr 15:53
amp photoshop curves Thomas Tonino 30 Mar 09:53
Piotr Legiecki
2002-03-29 11:37:37 UTC (almost 22 years ago)

amp photoshop curves

Hi

I wonder if it is possible to read amp photoshop curves? It would be very usefull for all who scan frequently, because there are some very intersting results after applying such a curve. They can gratly improve scan quality.

Some scanning gurus have created Excel profiles which generates different amp curves.

I know gimp can load/save curves from Curves dialog, but they can't be the photoshop ones ;-(

So I'd like to load amp files from photoshop from Curves window, just like native gimp curves.

Regards
Piotr Legiecki

regis rampnoux
2002-03-29 22:57:16 UTC (almost 22 years ago)

amp photoshop curves

Hi,

You can load the files with the plug-ins amp4gimp which is in the registery. (I found yesterday a bug but you can use it ...) There is no save option at this moment.

On 29-Mar-2002 Piotr Legiecki wrote:

Hi

I wonder if it is possible to read amp photoshop curves? It would be very
usefull for all who scan frequently, because there are some very intersting
results after applying such a curve. They can gratly improve scan quality.

Some scanning gurus have created Excel profiles which generates different amp
curves.

I know gimp can load/save curves from Curves dialog, but they can't be the
photoshop ones ;-(

So I'd like to load amp files from photoshop from Curves window, just like
native gimp curves.

Regards
Piotr Legiecki

_______________________________________________ Gimp-developer mailing list
Gimp-developer@lists.xcf.berkeley.edu http://lists.xcf.berkeley.edu/mailman/listinfo/gimp-developer

Branko Collin
2002-03-29 23:10:12 UTC (almost 22 years ago)

amp photoshop curves

On 29 Mar 2002, at 11:37, Piotr Legiecki wrote:

I wonder if it is possible to read amp photoshop curves? It would be very usefull for all who scan frequently, because there are some very intersting results after applying such a curve. They can gratly improve scan quality.

Some scanning gurus have created Excel profiles which generates different amp curves.

I know gimp can load/save curves from Curves dialog, but they can't be the photoshop ones ;-(

So I'd like to load amp files from photoshop from Curves window, just like native gimp curves.

Regis Rampnoux recently made a plug-in which can be found at . I am not sure I entirely
understand what it does, but it looks like it applies the curve directly, rather than converting it to a GIMP curve first.

I seem to remember he was working on another plug-in for Photoshop curves.

Robert L Krawitz
2002-03-30 00:48:06 UTC (almost 22 years ago)

amp photoshop curves

From: "Branko Collin"
Date: Fri, 29 Mar 2002 23:10:12 +0100

Regis Rampnoux recently made a plug-in which can be found at . I am not sure I entirely
understand what it does, but it looks like it applies the curve directly, rather than converting it to a GIMP curve first.

I seem to remember he was working on another plug-in for Photoshop curves.

I'd really like to see somebody do this as a front end to the Gimp-Print plugin (perhaps with some of the core incorporated into the Gimp-print core). I'll be happy to accept someone who wants to work on this onto the Gimp-print project.

With the current 8 bit only GIMP, this really needs to happen at the printing stage. Applying this kind of transform to 8-bit data means losing a lot of information; in 16 bits (which Gimp-print uses internally), this isn't a problem. Gimp-print has a 16-bit raw CMYK printing mode that's ideal for this kind of thing.

Karl Heinz Kremer
2002-03-30 02:06:23 UTC (almost 22 years ago)

amp photoshop curves

AMP file are very simple to read and to process: These "arbitrary map files" contain gamma tables with 256 byte values. The files contain either one or three (and possibly more) of these tables. A monochrome table would contain just one set of values, an RGB table would contain three sets.

Details can be found in the Adobe documentation of the Photoshop format (Adobe Photoshop 6.0 - File Formats Specification), which can be downloaded from Adobe's web site.

Adding this to either the Gimp curves tool or the Gimp-Print plug-in would be very simple.

Hope this helps,

Karl Heinz

On Fri, Mar 29, 2002 at 06:48:06PM -0500, Robert L Krawitz wrote:

From: "Branko Collin"
Date: Fri, 29 Mar 2002 23:10:12 +0100

Regis Rampnoux recently made a plug-in which can be found at . I am not sure I entirely
understand what it does, but it looks like it applies the curve directly, rather than converting it to a GIMP curve first.

I seem to remember he was working on another plug-in for Photoshop curves.

I'd really like to see somebody do this as a front end to the Gimp-Print plugin (perhaps with some of the core incorporated into the Gimp-print core). I'll be happy to accept someone who wants to work on this onto the Gimp-print project.

With the current 8 bit only GIMP, this really needs to happen at the printing stage. Applying this kind of transform to 8-bit data means losing a lot of information; in 16 bits (which Gimp-print uses internally), this isn't a problem. Gimp-print has a 16-bit raw CMYK printing mode that's ideal for this kind of thing.

regis rampnoux
2002-03-30 09:08:41 UTC (almost 22 years ago)

amp photoshop curves

On 29-Mar-2002 Robert L Krawitz wrote:

From: "Branko Collin"
Date: Fri, 29 Mar 2002 23:10:12 +0100 I seem to remember he was working on another plug-in for Photoshop curves.

The specs are not in the Photoshop SDK documentation...

I'd really like to see somebody do this as a front end to the Gimp-Print plugin (perhaps with some of the core incorporated into

It will be better to add the transformation after scaling the picture.

internally), this isn't a problem. Gimp-print has a 16-bit raw CMYK printing mode that's ideal for this kind of thing.

IMHO you should:
- add ICC profiles processing
- add processing of standard Gimp curves, they should applied after scaling the image and before the "adjust ouput" parameters. You must keep them working.

I have make a workflow to use hextone inks and soon VM inks (I should have the inks on wednesday because it is Easter time...). For these I use a Gimp curve that I apply before printing but it is before scaling which is not very good. I need to adjust output color AFTER because with Yellow I could choice cold or warm tone with VM inks.

I am not sure that 16 bits can improve really the printout but I am ready to test ;-)

The amp files seem deprecated for my use. I wrote the plug-in to print with hextone inks but I need to add a modifying/saving picture to make them usefull.

( my workflow is at http://www.regix.com/info/workflow.shtml )

Thomas Tonino
2002-03-30 09:53:21 UTC (almost 22 years ago)

amp photoshop curves

regis rampnoux wrote:

I'd really like to see somebody do this as a front end to the Gimp-Print plugin (perhaps with some of the core incorporated into

It will be better to add the transformation after scaling the picture.

In theory this will be better. But I wonder how much it will matter in practive, when printouts are made with a decent resolution. IMO the difference will be much more subtle than with a.g. alpha blending. I think ICC processing usually interpolates between relatively few colors it knows how to transform.

And it can be worked around by scaling an image up yourself, if the resolution is so low that it matters.

internally), this isn't a problem. Gimp-print has a 16-bit raw CMYK printing mode that's ideal for this kind of thing.

IMHO you should:
- add ICC profiles processing

Is there infrastructure in the Gimp for ICC profiles (i.e. profiles read on file open, etc)? IMO ICC mostly makes sense if done right. ICC in a print plugin only will remain a hack (transform from sRGB or some other monitor profile into printer space) while it may be better to stick to the color space of the source material if that has a wider gamut.

If ICC is slapped on at the tail of processing it may as well be a separate filter. Pity that 16 bit CMYK is cannot be used then. Grr. Thus the need to integrate processing into the print plugin. Still I'd like at least the source profile to come from the Gimp; there are enough printer settings as is. And if gimp-print is behind a spooler and printing images from different sources, there is no way to tell it the source profile, while the destination profile (and rendering intent etc) is entirely reasonable to set.

BTW is there a standard for this kind of stuff? When printing to Postscript, amd processing in Ghostscript, I'd guess the ICC profiels are lost in the output bitmap. Where is that usually normalized?

- add processing of standard Gimp curves, they should applied after scaling the image and before the "adjust ouput" parameters. You must keep them working.

Can you explain why the curves must take effect after scaling? Scaling should happen in linear reflectivity space (i.e. the interpolated colors do not alter the average density or color). I would be surprised if that was true, as it would involve a transform from screen RGB (gamma!) to 16 bit linear RGB, the curves, then to the non linear printer space. Seems best tacked onto an ICC processor.

Thomas

Robert L Krawitz
2002-03-30 14:32:45 UTC (almost 22 years ago)

amp photoshop curves

Date: Sat, 30 Mar 2002 09:08:41 +0100 (CET) From: regis rampnoux

I am not sure that 16 bits can improve really the printout but I am ready to test ;-)

The problem with 8 bits isn't that the number of discrete levels is too small, but that some of the intervals (in *linear* 8-bit space) are too great. This is particularly noticeable in the highlights -- there's a huge difference between 0 and 1/256 coverage, for example. So what typically happens is that you wind up with multiple input levels mapped to output level 0, 1, and 2, and you get very visible steps between levels.

If the transform were done within Gimp-print, in 16-bit space, this rounding error would be insignificant.

Karl Heinz Kremer
2002-03-30 14:50:52 UTC (almost 22 years ago)

amp photoshop curves

On Sat, Mar 30, 2002 at 09:08:41AM +0100, regis rampnoux wrote:

On 29-Mar-2002 Robert L Krawitz wrote:

From: "Branko Collin"
Date: Fri, 29 Mar 2002 23:10:12 +0100 I seem to remember he was working on another plug-in for Photoshop curves.

The specs are not in the Photoshop SDK documentation...

Check the "Adobe Photoshop 6.0 File Formats Specification - Version 6.0 Release 2 November 2000". The file I have is named ps6ffspecsv2.pdf, and I think it came with the SDK, but I could be wrong. All the SDK documentation files can be downloaded individually from Adobe's web site.

The description is on page 49.

Karl Heinz

Nick Lamb
2002-03-30 21:48:42 UTC (almost 22 years ago)

amp photoshop curves

On 29 Mar 2002, at 11:37, Piotr Legiecki wrote:

So I'd like to load amp files from photoshop from Curves window, just like native gimp curves.

On Fri, Mar 29, 2002 at 11:10:12PM +0100, Branko Collin wrote:

Regis Rampnoux recently made a plug-in which can be found at . I am not sure I entirely
understand what it does, but it looks like it applies the curve directly, rather than converting it to a GIMP curve first.

I seem to remember he was working on another plug-in for Photoshop curves.

Does Gimp 1.3 work include making it possible (easier? maybe it was already possible) to provide plug-ins/ modules that make Gimp understand more + different types of palette, gradient, brush etc. automagically? ie You install a "FooPaint brush add-on" and then FooPaint brushes can be placed in $DATADIR/foopaint-brushes or something to make them appear in amongst ordinary Gimp brushes...

ISTR that in Gimp 1.0 I found it hard to add this sort of thing without hacking the core, but obviously I'm not up to speed with 1.3 yet :)

Nick.

Nathan C Summers
2002-03-31 10:23:41 UTC (almost 22 years ago)

amp photoshop curves

On Sat, 30 Mar 2002, Nick Lamb wrote:

On 29 Mar 2002, at 11:37, Piotr Legiecki wrote:

Does Gimp 1.3 work include making it possible (easier? maybe it was already possible) to provide plug-ins/ modules that make Gimp understand more + different types of palette, gradient, brush etc. automagically? ie You install a "FooPaint brush add-on" and then FooPaint brushes can be placed in $DATADIR/foopaint-brushes or something to make them appear in amongst ordinary Gimp brushes...

ISTR that in Gimp 1.0 I found it hard to add this sort of thing without hacking the core, but obviously I'm not up to speed with 1.3 yet :)

Most of this can be done already done already with a regular plug-in or script, but not all; there are some necessary missing pdb functions. File a bug on bugzilla.gnome.org and I'll get around to implementing the functions as soon as I finish up with the tool plug-in work.

Rockwalrus

regis rampnoux
2002-04-02 20:51:47 UTC (almost 22 years ago)

amp photoshop curves

On 30-Mar-2002 Karl Heinz Kremer wrote:

The specs are not in the Photoshop SDK documentation...

Check the "Adobe Photoshop 6.0 File Formats Specification - Version 6.0
Release 2 November 2000". The file I have is named ps6ffspecsv2.pdf, The description is on page 49.

I have the same, but I have yet wrote a plug-in to read amp files, I was trying to load *.acv files now ;-) Curves for some special inks exists in this format only.

I am trying to write a plug-in which can give a first curve corresponding to a ink/paper set.

Austin Donnelly
2002-04-04 12:43:34 UTC (almost 22 years ago)

amp photoshop curves

On Friday, 29 Mar 2002, regis rampnoux wrote:

You can load the files with the plug-ins amp4gimp which is in the registery. (I found yesterday a bug but you can use it ...) There is no save option at this moment.

If the amp format is simple enough, why don't we just make it the default format for Gimp curves too?

Austin

Sven Neumann
2002-04-04 15:53:24 UTC (almost 22 years ago)

amp photoshop curves

Hi,

Nathan C Summers writes:

[...] as soon as I finish up with the tool plug-in work.

actually Mitch and me are not overly happy with your recent commit. It appears that your code was based on an outdated version of the tools code so your commit seems to remove some of the fixes Mitch applied lately. You also removed some stuff like cursor changing etc. that was finally working. Our plan was to finally approach 1.4, not to steer the ship away from it evenb further.

You catched us on the road to Guadec, so we haven't been able to react earlier and we haven't had much chance to look at the changes in detail. Hopefully we'll find some time to evaluate the changes in more depth tomorrow after our talk. At the moment, I'm favoring to back the tool plug-in changes out of the HEAD branch and to apply it to a separate branch so we have a chance to finish cleaning up and stabilizing the tools while you can continue to develop the tool plug-in infrastructure at the same time. More thoughts on this tomorrow...

Salut, Sven

Guillermo S. Romero / Familia Romero
2002-04-04 17:31:39 UTC (almost 22 years ago)

amp photoshop curves

austin@gimp.org (2002-04-04 at 1143.34 +0100):

If the amp format is simple enough, why don't we just make it the default format for Gimp curves too?

The problem I see is that it means not under GIMP people control (basicaly about improving, I doubt the format would change). For example, when moving to 16 bits or other modes, I do not see PS AMP 256 entries LUT or GIMP 17 entry curves as the way to go. It sounds absurd to work in such high mode and then limit other things to brute approximations.

Or think about supporting extra channels, AMP only supports one or three channels. Leaving room for improvement should be taken into account. I think it is better to write an external converter (uum, it already exists :] ) than support two formats or discard current (is there any gimp2amp?) and then try to workaround problems in the future.

GSR

regis rampnoux
2002-04-04 19:42:21 UTC (almost 22 years ago)

Curves files

On 04-Apr-2002 Guillermo S. Romero / Familia Romero wrote:

example, when moving to 16 bits or other modes, I do not see PS AMP 256 entries LUT or GIMP 17 entry curves as the way to go. It sounds absurd to work in such high mode and then limit other things to brute approximations.

I have a question about this limitation: why the Gimp spline curves is limited to 17 entries and the procedure gimp-curves-spline use a 32 items array of points?
May be it is not the same goal but that is the difference?

Guillermo S. Romero / Familia Romero
2002-04-04 22:20:40 UTC (almost 22 years ago)

Curves files

regisr@regix.com (2002-04-04 at 1942.21 +0200):

I have a question about this limitation: why the Gimp spline curves is limited to 17 entries and the procedure gimp-curves-spline use a 32 items array of points?
May be it is not the same goal but that is the difference?

Code from the file, it reads 16 pairs:

for (j = 0; j < 17; j++) {
fields = fscanf (f, "%d %d ", &index[i][j], &value[i][j]); if (fields != 2)
{
g_print ("fields != 2");
return FALSE;
}
}

Umm, hehehe, it reads 16 pairs, x and y values, not 17 (< 17, not with my grep and coding skills.

GSR

David Odin
2002-04-04 23:09:59 UTC (almost 22 years ago)

Curves files

On Thu, Apr 04, 2002 at 10:20:40PM +0200, Guillermo S. Romero / Familia Romero wrote:

regisr@regix.com (2002-04-04 at 1942.21 +0200):

I have a question about this limitation: why the Gimp spline curves is limited to 17 entries and the procedure gimp-curves-spline use a 32 items array of points?
May be it is not the same goal but that is the difference?

Code from the file, it reads 16 pairs:

for (j = 0; j < 17; j++) {
fields = fscanf (f, "%d %d ", &index[i][j], &value[i][j]); if (fields != 2)
{
g_print ("fields != 2");
return FALSE;
}
}

Umm, hehehe, it reads 16 pairs, x and y values, not 17 (< 17, not with my grep and coding skills.

More than you think ;-)
from 0 to 16, that's seventeen values!

Guillermo S. Romero / Familia Romero
2002-04-04 23:14:37 UTC (almost 22 years ago)

Curves files

David@dindinx.org (2002-04-04 at 2309.59 +0200):

something about the curve widget, I guess, but today I am a bit "obtuse" with my grep and coding skills.

More than you think ;-)
from 0 to 16, that's seventeen values!

Can I delete this day? :]

GSR

regis rampnoux
2002-04-05 00:24:05 UTC (almost 22 years ago)

Curves files

On 04-Apr-2002 Guillermo S. Romero / Familia Romero wrote:

from 0 to 16, that's seventeen values!

Can I delete this day? :]

Days are deleted when deprecated ;-)

But why 17? ( why not? ) My question was why 17 points in curves.c and gimp_curves_spline accept an array of 32 points ?

What are the diff between the curves in curves.c and color_cmds.c ?

Sven Neumann
2002-04-05 15:52:54 UTC (almost 22 years ago)

Curves files

Hi,

regis rampnoux writes:

On 04-Apr-2002 Guillermo S. Romero / Familia Romero wrote:

from 0 to 16, that's seventeen values!

Can I delete this day? :]

Days are deleted when deprecated ;-)

But why 17? ( why not? ) My question was why 17 points in curves.c and gimp_curves_spline accept an array of 32 points ?

What are the diff between the curves in curves.c and color_cmds.c ?

well, gimp_curves_spline actually accepts an array of 32 integers, not points. Our spline curves are limited to 17 points (for no good reason except simplicity), so the maximal number of points should probably be 34. IMO this is simply a bug. I don't think we should fix it in gimp-1.2 since it would mean that newer plug-ins/scripts that depend on this feature won't work correctly on older 1.2 versions, but it should be definitely be fixed in 1.3. Would you mind filing a bug-report so we don't forget? A patch would be nice to have too (you need to change the .pdb file, not color_cmds.c).

Salut, Sven