Bug 134919 - CMYK <-> RGB conversion generates the same color
Summary: CMYK <-> RGB conversion generates the same color
Status: RESOLVED NOTABUG
Alias: None
Product: LibreOffice
Classification: Unclassified
Component: LibreOffice (show other bugs)
Version:
(earliest affected)
6.4.5.2 release
Hardware: All All
: medium normal
Assignee: Not Assigned
URL:
Whiteboard:
Keywords:
Depends on:
Blocks:
 
Reported: 2020-07-18 02:09 UTC by Leandro Martín Drudi
Modified: 2020-07-18 17:00 UTC (History)
1 user (show)

See Also:
Crash report or crash signature:


Attachments
This comparison was made in a bitmap so that there are no problems with any color conversion when exporting. (1.45 MB, image/bmp)
2020-07-18 02:10 UTC, Leandro Martín Drudi
Details
Convertion in LibreOffice writing RGB or CMYK values. (14.88 KB, image/png)
2020-07-18 02:11 UTC, Leandro Martín Drudi
Details
Convertion in illustrator (6.33 KB, image/png)
2020-07-18 02:12 UTC, Leandro Martín Drudi
Details

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Description Leandro Martín Drudi 2020-07-18 02:09:09 UTC
Description:
When you write the values to generate a pure color (Green, Red, or Blue), it becomes an RGB value of 255 when they should be different values.

Steps to Reproduce:
1. Clic on font color -> Custom color
2. Write: C-0, M-100, Y-100, K-0
OR
3. Write: C-100, M-100, Y-0, K-0
OR
4. Write: C-100, M-0, Y-100, K-0

Actual Results:
For 2: R=255, G=0, B=0
For 3: R=0, G=0, B=255
For 4: R=0, G=255, B=0

Expected Results:
For 2: R=227, G=6, B=19 (or similar)
For 3: R=49, G=39, B=131 (or similar)
For 4: R=0, G=150, B=64 (or similar)
Values obtained from Illustrator.


Reproducible: Always


User Profile Reset: No



Additional Info:
This conversion happens the same if we put an RGB value: 255, 0, 0 will convert to 100 values when they are not really correct.
RED CMYK from 255, 0, 0 in RGB: 0%, 95%, 91%, 0%
GREEN CMYK from 0, 255, 0 in RGB: 65%, 0%, 100%, 0%
BLUE CMYK from 0, 0, 255 in RGB: 93%, 75%, 0%, 0%
Values obtained from Illustrator.

This is a problem because the colors that we will see in the documents will not be real and if the objective is to print, the result could be quite different.
Comment 1 Leandro Martín Drudi 2020-07-18 02:10:04 UTC
Created attachment 163217 [details]
This comparison was made in a bitmap so that there are no problems with any color conversion when exporting.
Comment 2 Leandro Martín Drudi 2020-07-18 02:11:03 UTC
Created attachment 163218 [details]
Convertion in LibreOffice writing RGB or CMYK values.
Comment 3 Leandro Martín Drudi 2020-07-18 02:12:05 UTC
Created attachment 163219 [details]
Convertion in illustrator

There is no CorelDraw capture because they are not unified in the same dialog, but independently.
Comment 4 Regina Henschel 2020-07-18 11:02:46 UTC
I think, the error is in handling Illustrator. Please try any of the online convertes with RGB#E30613 or with CMYK(0 100 100 0) to see that these values define different colors.
Comment 5 Leandro Martín Drudi 2020-07-18 14:45:14 UTC
Of course, undoubtedly a software for excellence in color management for design is wrong. Sorry.
https://helpx.adobe.com/illustrator/using/color.html
Comment 6 Regina Henschel 2020-07-18 17:00:16 UTC
I have not said, that Illustrator is wrong. But you might not have considered that conversion in Illustrator uses color profiles.

CMYK values are not used inside LibreOffice, but they are only an input help in the dialogs. And LibreOffice does not use color profiles at all. If you do not like "NOTABUG", read it as "WONTFIX".