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Colour issue when converting from CMYK to RGB
Rank: Newbie
Groups: Guest
Joined: 6/3/2016(UTC)
Posts: 2
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I am converting a jpeg image with a colour profile of : Coated FOGRA39 (ISO 12647-2:2004) to RGB with a colour profile of sRGB using the following code: Code:private sub ConvertToRGB(byref img as Aurigma.GraphicsMill.bitmap, profile as string)
'Choose LittleCMS color management engine
img.ColorManagement.ColorManagementEngine = Aurigma.GraphicsMill.Transforms.ColorManagementEngine.LittleCms
if profile = "" andAlso img.IsCMYK then
'Assign output RGB profile for conversion
img.ColorManagement.RgbColorProfile = Aurigma.GraphicsMill.ColorProfile.FromSrgb
elseif profile <> "" then
profile = "C:\windows\system32\spool\drivers\color\" & profile & ".icc"
try
img.ColorManagement.RgbColorProfile = New Aurigma.GraphicsMill.ColorProfile(profile)
catch e as exception
throw new Exception("Could not find RGB Colour Profile: " & e.message)
end try
end if
if img.colorProfile is nothing then
if img.isRGB then
img.ColorProfile = Aurigma.GraphicsMill.ColorProfile.FromSrgb
else
img.ColorProfile = new ColorProfile("C:\windows\system32\spool\drivers\color\RSWOP.icm")
end if
end if
'Convert to RGB
if img.ColorManagement.RgbColorProfile isnot nothing then
img.ColorManagement.ConvertToContinuous(Aurigma.GraphicsMill.ColorSpace.Rgb, False, img.IsExtended)
end if
end sub
It seems that the red in the converted image is much brighter. See attached   Not sure if there is something that can be done about this or if this is expected when converting between these colour profiles? Edited by user Wednesday, September 27, 2017 2:36:29 AM(UTC)
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Rank: Advanced Member
Groups: Guest
Joined: 9/19/2006(UTC)
Posts: 505
Was thanked: 41 time(s) in 41 post(s)
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Hi Ben, It looks like your version of GM is pretty old. I tried your image with the recent version, and it worked fine. Here is my code: Code:using (var bitmap = new Bitmap("Original CMYK image.jpg"))
{
bitmap.ColorManagement.DestinationProfile = ColorProfile.FromSrgb();
bitmap.ColorManagement.ColorManagementEngine = ColorManagementEngine.LittleCms;
bitmap.ColorManagement.Convert(PixelFormat.Format24bppRgb);
bitmap.Save("Converted RGB image_GM9.jpg");
}
And here is the output: 
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Best regards, Eugene Kosmin The Aurigma Development Team |
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Rank: Newbie
Groups: Guest
Joined: 6/3/2016(UTC)
Posts: 2
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Hi Sorry, forgot to mention that we are using Graphics Mill 5.5.6.0. Our application won't compile with different versions of the Graphics Mill component so we are stuck with version 5 for now. Do you know if they is anything we can try to get this working with version 5 or is this just a limitation with this version? Thanks, Ben
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Rank: Advanced Member
Groups: Guest
Joined: 9/19/2006(UTC)
Posts: 505
Was thanked: 41 time(s) in 41 post(s)
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My Photoshop CS6 gives me a warning about invalid ICC profile when I open the original image. Maybe this is a cause of the problem. Since the 6x versions, color management workflow was significantly changed, and I guess that's why the image can be handled with elder versions. I don't think there is something you can do with GM 5. The version you have is the latest 5x. And I'm not sure how did you get your result. When I tried to run the code with GM5, I got CMInappropriateProfileException without any output. |
Best regards, Eugene Kosmin The Aurigma Development Team |
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Colour issue when converting from CMYK to RGB
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