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Old 10-17-2024, 02:08 PM
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Kugelfang Kugelfang is offline
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Hmmm... color differences between applications?

So here's an interesting observation. I'm working on Heinkel's Baltimore model. I have the print-it-yourself version. I wanted to alter some of the coloring. I wanted the hull bottom to be a brighter red rather than the rust brown as it was designed.


So I was able to import selected pages of the original *.pdf file into Inkscape and edit the underlying svg to change the color of the hull skin but I did not touch the other parts. I printed the involved page directly from Inkscape on my Brother color laser printer and was quite happy with the vivid colors and deep blacks throughout the printout.


As I progressed on the model I needed to print out the next page but I didn't need to alter any colors so I printed it straight from the pdf viewer installed on my computer. I'm pretty sure that I used exactly the same printer settings yet the colors on the second printout were somewhat washed out and not nearly as vivid. Not very satisfying, to tell the truth. The blacks and yellows on the second print weren't very close to the first print at all.



Has anyone else seen different print colors depending on the program used to print? Same printer, same printer settings, same card stock, but different colors. Hmmm....
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Old 10-17-2024, 03:53 PM
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Not exactly. However, from noticing that the print colours (British printers automatically add the extra u) typically came out darker than screen, I discovered a setup option in advanced print preferences. This selects whether color (US software) management is handled by the host system or the printer, and can be set to graphics/proof/match and one other option. It might be what fixes this for you.
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Old 10-18-2024, 08:04 AM
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I'm no expert, just throwing this out there...

If the original file was meant for a book run at a printers, say a lithographic print process, it would be saved as CMYK, wouldn't it?.

So without editing and resaving into a slightly different format, you got the original CMYK printout straight from the PDF.
Whereas your edited version may have been resaved as RGB, or at least outputted as RGB (altering the colour).

Just spit-balling.
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Old 10-19-2024, 02:28 AM
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Thanks, guys.



I think you guys may very well be on the right track. Inkscape seems to have a multitude of color profiles. I doubt that 'Xreader' (my default pdf viewer) has much in the way of color management. I'm assuming Inkscape is assigning a profile (which may not be what the original was designed in) when it converts the file to svg.



Interesting. But not worth a lot of time to investigate, IMO.
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Old 10-21-2024, 12:09 AM
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Maybe the printer toner was reloaded just before your first printing and pretty exhausted before the second one?

Another possibility is the printer itself and the positioning of the sheet. In my office I had an A4/A3 CANON printer and I used it sometimes when I need an A3 print. I found however that the color shades differed from one end of a sheet to the other. Especially grays and greens were visibly warm at the top and cold at the bottom of the same sheet. The problem was never fixed although the printer was regularly maintained and few times repaired. Finally it was replaced with other CANON device, which secures more homogenous pigment density.
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Old 10-26-2024, 11:18 AM
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Kugelfang Kugelfang is offline
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The printer seems to give nice consistent results. So it certainly seems to be the import into Inkscape that makes the difference. I don't completely understand the reasons but I'm happy with the results.


I also suspect that the USS Baltimore model from Heinkel I'm working on was originally in some type of vector (SVG?) format exported from CorelDraw. So I think when exported to PDF, the underlying SVG vector code is wrapped inside the PDF. If the artwork was in a raster format I suspect I'd see more consistency between applications.
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Old 10-26-2024, 02:23 PM
Laurence Finston Laurence Finston is offline
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You can check the colors in an image file by using the `convert' command from the ImageMagick package as below. (The file isn't converted or changed in any way.)

I made two versions of an image containing a single square of RGB red, one in EPS and one in SVG. I generated each one directly, I didn't convert one to the other.

I also included the EPS file in a document to create a PDF.

The following are the calls to `convert' with the terminal output:

convert ttemp_0000.svg -unique-colors -depth 8 txt:
# ImageMagick pixel enumeration: 1,1,255,srgba
0,0: (255,0,0,255) #FF0000FF red

lf@lf-B365M-D3H:~/3DLDF-3.0/src$ convert ttemp_0000.eps -unique-colors -depth 8 txt:
# ImageMagick pixel enumeration: 1,1,255,srgba
0,0: (255,0,0,255) #FF0000FF red

lf@lf-B365M-D3H:~/3DLDF-3.0/src$ convert ttemp.pdf -unique-colors -depth 8 txt:
# ImageMagick pixel enumeration: 7,1,255,srgba
0,0: (255,0,0,255) #FF0000FF red
1,0: (255,0,0,187) #FF0000BB srgba(255,0,0,0.733333)
2,0: (255,0,0,136) #FF000088 srgba(255,0,0,0.533333)
3,0: (255,0,0,68) #FF000044 srgba(255,0,0,0.266667)
4,0: (255,0,0,51) #FF000033 srgba(255,0,0,0.2)
5,0: (255,0,0,34) #FF000022 srgba(255,0,0,0.133333)
6,0: (255,255,255,0) #FFFFFF00 srgba(255,255,255,0)

I then generated the EPS version again, this time with CMYK red, i.e., (0, 1, 1, 0) using MetaPost's syntax. This is the result:

convert ttemp_0000.eps -unique-colors -depth 8 txt:
# ImageMagick pixel enumeration: 1,1,255,srgba
0,0: (237,28,36,255) #ED1C24FF srgba(237,28,36,1)

I don't know why the values in the second line of the output aren't (0, 255, 255, 0). However, the color is red, though it seems to be darker than the RGB red.
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Old 10-26-2024, 06:04 PM
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I concur with Dave, I always have to be mindful of intended output.
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Old 10-27-2024, 02:11 AM
Laurence Finston Laurence Finston is offline
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I've attached three PDF files with color samples along with their RGB or CMYK values. They can be used for testing the results of a given printer. The source code is available here: src - 3dldf.git - 3DLDF and here: Colors << src - 3dldf.git - 3DLDF, respectively.

In this article: https://www.tug.org/TUGboat/tb44-3/t...n-alhambra.pdf
there's a section about color and specifically the technique of color replacement. It may contain some information relevant to your problem.
Attached Files
File Type: pdf color_test.pdf (7.3 KB, 5 views)
File Type: pdf rgb_test.pdf (32.2 KB, 4 views)
File Type: pdf cmyk_test.pdf (36.3 KB, 3 views)
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