Legacy ImageMagick Discussions Archive

In my system the preview of the photos in CMYK are not correctly displayed. Some colors are shown more intense.
For example, the green color becomes a very strong and luminous green.
My system using Imagemagick with this commands:
DNG_IMAGEMAGICK_PREVIEW_SETTINGS : -intent relative -sample 1024x768> -quality 95 -colorspace sRGB -strip -auto-orient -density 72
DNG_IMAGEMAGICK_THUMBNAIL_SETTINGS : -intent relative -sample 500x375> -quality 95 -colorspace sRGB -strip -auto-orient -density 72

Do I have to change any value in the parameters? If yes, which one?

If your photo does not contain an embedded ICC profile, then software needs to guess what colours need to be shown, and will probably guess wrong.

If it does contain an ICC profile, you should convert to an sRGB or other profile with the "-profile" operation, not "-colorspace".

"identify -verbose" will show if there is an embedded profile.

Thanks a lot for the reply.

My photo contain an ICC profile. Below "identify -verbose" result:
photoshop:ICCProfile: Coated FOGRA27 (ISO 12647-2:2004)

If I convert the photo to an sRGB, the photo is display correctly. But I need to display the CMYK colorspace correctly.
From the support service of my system, they told me to change the value of "-density" , is possible?

Annalisa wrote:If I convert the photo to an sRGB, the photo is display correctly. But I need to display the CMYK colorspace correctly.

I don't understand what you mean. Computer displays work with the additive RGB process, not the subtractive CMYK process. When a CMYK image is shown in a computer screen, it must first be converted to an appropriate RGB colourspace.

Annalisa wrote:From the support service of my system, they told me to change the value of "-density" , is possible?

"-density" will make no difference to the colours. What is your input? If a vector such as PDF, then "-density" will make a difference to the resolution.

My input is a photo .jpg.

"identify -verbose" show:

Image: foto_test.jpg
Format: JPEG (Joint Photographic Experts Group JFIF format)
Mime type: image/jpeg
Class: DirectClass
Geometry: 5616x3744+0+0
Resolution: 300x300
Print size: 18.72x12.48
Units: PixelsPerInch
Colorspace: CMYK
Type: ColorSeparation
Base type: Undefined
Endianess: Undefined
Depth: 8-bit
Channel depth:
Cyan: 8-bit
Magenta: 8-bit
Yellow: 8-bit
Black: 8-bit
Channel statistics:
Pixels: 21026304
Cyan:
min: 0 (0)
max: 255 (1)
mean: 139.259 (0.546115)
standard deviation: 52.4773 (0.205793)
kurtosis: 0.2268
skewness: -0.341628
entropy: 0.937418
Magenta:
min: 0 (0)
max: 255 (1)
mean: 131.278 (0.514814)
standard deviation: 58.388 (0.228973)
kurtosis: -0.399081
skewness: -0.376988
entropy: 0.963539
Yellow:
min: 0 (0)
max: 255 (1)
mean: 114.246 (0.448025)
standard deviation: 60.0831 (0.23562)
kurtosis: -0.418208
skewness: -0.0561591
entropy: 0.946153
Black:
min: 0 (0)
max: 255 (1)
mean: 70.9633 (0.278288)
standard deviation: 80.8589 (0.317094)
kurtosis: -0.714992
skewness: 0.878803
entropy: 0.860158
Image statistics:
Overall:
min: 0 (0)
max: 255 (1)
mean: 113.937 (0.44681)
standard deviation: 62.9518 (0.24687)
kurtosis: -0.927151
skewness: -0.138571
entropy: 0.926817
Total ink density: 372.549%
Rendering intent: Perceptual
Gamma: 0.454545
Chromaticity:
red primary: (0.64,0.33)
green primary: (0.3,0.6)
blue primary: (0.15,0.06)
white point: (0.3127,0.329)
Matte color: grey74
Background color: white
Border color: srgb(223,223,223)
Transparent color: none
Interlace: None
Intensity: Undefined
Compose: Over
Page geometry: 5616x3744+0+0
Dispose: Undefined
Iterations: 0
Compression: JPEG
Quality: 90
Orientation: Undefined
Properties:
date:create: 2019-02-07T10:24:37+01:00
date:modify: 2019-02-07T14:28:36+01:00
dc:format: image/tiff
icc Copyright 2004, 2006 Adobe Systems, Inc.
icc:description: Coated FOGRA27 (ISO 12647-2:2004)
jpeg:colorspace: 4
jpeg:sampling-factor: 1x1,1x1,1x1,1x1
photoshop:ColorMode: 4
photoshop:DateCreated: 2011-04-13T19:55:35
photoshop:ICCProfile: Coated FOGRA27 (ISO 12647-2:2004)
signature: 6b49fd1b9b8e40256885112bce698eaadd58b21cfb6d76c50a55c76f0a45b319
xmp:CreateDate: 2011-04-13T19:55:35
xmp:CreatorTool: Adobe Photoshop CS5 Macintosh
xmp:MetadataDate: 2011-10-28T10:20:13+02:00
xmp:ModifyDate: 2011-10-28T10:20:13+02:00
xmpMM:DocumentID: xmp.did:9425904450206811ACAFD7B9293B326F
xmpMM:InstanceID: xmp.iid:CD08C9D7082068118C149F6FA5A2E5D9
xmpMM:OriginalDocumentID: xmp.did:9425904450206811ACAFD7B9293B326F
Profiles:
Profile-8bim: 9916 bytes
Profile-icc: 557120 bytes
Profile-xmp: 15473 bytes
Artifacts:
verbose: true
Tainted: False
Filesize: 14.6518MiB
Number pixels: 21.0263M
Pixels per second: 53.7935MP
User time: 0.391u
Elapsed time: 0:01.390
Version: ImageMagick 7.0.8-26 Q16 x64 2019-02-05 http://www.imagemagick.org

Sorry, but I know little about this subject and I do not know how to explain myself.
The problem is that in my system of "Asset Management" the photo preview is not correct, because the colors change.
With the same photo in another system don't have this problem.

Annalisa wrote:The problem is that in my system of "Asset Management" the photo preview is not correct, because the colors change.

If you use "-colorspace sRGB", yes, the colours will be wrong. Instead, you should use "-profile sRGB.icc" or similar.

I know nothing about your "Asset Management" or your computer. Many software systems will correctly display photos that have embedded profiles, even CMYK profiles. However, some CMYK colours cannot be shown on sRGB displays, so there will usually be some change.