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Colour Conversion - Numerical Values


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Hi

I've been testing Affinity Photo (AP), and about to test Affinity Designer.

This is a general question, part of which is an analysis I'm doing, after answering someones technical question on LinkedIn.

The author of the post was confused with getting varying numeric values from CMYK to RGB and HEX

I used AP to try out the colour sliders and chooser interface.

Can anyone answer why values differ from a given CMYK value?

Example: CMYK 65 0 100 0

AP Sliders = LAB 89 -70 82 / RGB 89 255 0 / HSL 99 100 50 / WEB RGB 59FF00

AP Chooser = LAB NIL / RGB 128 177 62 / HSL 86 48 47 / # HEX (CSS) 80B13E

 

If anyone is interested, I have created a spreadsheet of my other findings.

 

Ideas, thoughts?

 

Dee

iMac Pro (2017) Processor: 3GHz 10-Core Intel Xeon W / Memory: 64 GB 2666 MHz DDR4 / Graphics: Radeon Pro Vega 64 16 GB | iPad Pro: 12.9 inch 2nd Gen

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Hi Dee,

 

I haven't been able to replicate this issue at my end. Would it be possible for you to give me more information so I can try and investigate this further for you? :)

 

Thanks

C

Please tag me using @ in your reply so I can be sure to respond ASAP.

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Hi Callum

Good to hear from a moderator. Is this how to reply directly to you? Still new to this forum.

So, you can't replicate? Interesting. The only way I can imagine communicating what I'm doing to achieve these results, is to create a Screen Recording. Is there a favoured media type for the movie I'll be adding to the Affinity Forum Media Library?

Dee

iMac Pro (2017) Processor: 3GHz 10-Core Intel Xeon W / Memory: 64 GB 2666 MHz DDR4 / Graphics: Radeon Pro Vega 64 16 GB | iPad Pro: 12.9 inch 2nd Gen

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To add to the mystery. Just installed trial of Affinity Designer (AD). This app also has discrepancies between Slider and Chooser values. You're not alone, Affinity! Adobe does this, too! Only with different values.

 

Anyhoo, just purchased your Affinity Photo. 20% OFF on your first birthday. I couldn't turn that down! Is there a birthday coming for Designer, or has that passed already? Not that I'm cheap or anything! :D

iMac Pro (2017) Processor: 3GHz 10-Core Intel Xeon W / Memory: 64 GB 2666 MHz DDR4 / Graphics: Radeon Pro Vega 64 16 GB | iPad Pro: 12.9 inch 2nd Gen

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Hi deeland,

 

I'm not sure if I'm right in my assumption, but I'm guessing that you're applying a given CMYK colour value to an object in your document, then looking at what the sliders say for different colour models, then sampling the colour back again and looking what the sliders for the different colour models now say?

 

If so, this is the source of your problems...

 

The document is in one concrete colour space (whatever you chose from Document Setup), so the moment you sample the colours back, you get a colour in that colour space. If you apply that colour to the object and then read back the sliders, you get a colour from that colour space converted into each of those other formats - the conversion is not a lossless two-way process (it really cannot be) and will result in different values.

 

Please let us know if that's not the problem and I'm sure we can help :)

 

Thanks,

Matt

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Matt

 

I wish it was that simple. Nothing to do with colour profiles/spaces etc. Purely dialling in a CMYK numerical value, create a swatch, then comparing numerical values between Slider and Chooser windows.

 

Dee

iMac Pro (2017) Processor: 3GHz 10-Core Intel Xeon W / Memory: 64 GB 2666 MHz DDR4 / Graphics: Radeon Pro Vega 64 16 GB | iPad Pro: 12.9 inch 2nd Gen

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I´d also say we don´t have a special issue here, different numbers of input and color picker are to be expected 

 

you just can´t replicate every CMYK value in an RGB color space or not every LAB value in a RGB color space

- at the point where you input the LAB/CMYK value, it is transformed into the closest matching RGB value http://www.cambridgeincolour.com/tutorials/color-space-conversion.htm (btw: which settings do you use, MattP? the ones specified in preferences?)

 

but I do think there is an issue with the conversion itself which is discussed here in it´s affect on Dodge and Burn where neutral grey get´s converted to something that is not neutral anymore

https://forum.affinity.serif.com/index.php?/topic/13314-dodge-and-burn-with-overlay-neutral-color-50-grey/?p=99929

 

 

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I don't want to give folks here the impression I'm completely new to everything. Just new to Affinity. I've lost patience with Adobe, and am looking to move away from their monopoly. Not exactly possible in today's industry, Adobe is quite ubiquitous, unfortunately. Nevertheless, these tests I'm carrying out are just another visit to tests I've carried out over the years with various software applications. I've uncovered Pantone swatch errors in Adobe apps, years ago. This though, is something I never expected. Seems so simple.

 

MBd — you've reached too far in this instance. I'm talking about a very simple scenario, where the user has a reasonable expectation of consistent values, in the same document, from the same swatch, between two ways of choosing colours: the Colour Sliders Values and the Colour Chooser Values. I think that's a fair expectation, don't you? No conversions, just straight forward, dialled in value, then inspection of said value.

iMac Pro (2017) Processor: 3GHz 10-Core Intel Xeon W / Memory: 64 GB 2666 MHz DDR4 / Graphics: Radeon Pro Vega 64 16 GB | iPad Pro: 12.9 inch 2nd Gen

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Okay, I think the main point here is: How are you 'inspecting' the values? Using what and where? I'm sure we can help you, but I don't know what you're using to 'see' the values that you're expecting and where you're getting the other values from that you expected it to be? :)

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… I don't know what you're using to 'see' the values that you're expecting and where you're getting the other values from that you expected it to be?

 

MattP

 

You're a worry! :D Like I said, the Colour Slider compared to the Colour Chooser. I'm going to make a Screen Recording, and hopefully post it here. Watch this space …

iMac Pro (2017) Processor: 3GHz 10-Core Intel Xeon W / Memory: 64 GB 2666 MHz DDR4 / Graphics: Radeon Pro Vega 64 16 GB | iPad Pro: 12.9 inch 2nd Gen

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Well, movie is made, but I get the following error message:

"Error You aren't permitted to upload this kind of file"

 

Any ideas what movie file types are allowed for uploading here?

iMac Pro (2017) Processor: 3GHz 10-Core Intel Xeon W / Memory: 64 GB 2666 MHz DDR4 / Graphics: Radeon Pro Vega 64 16 GB | iPad Pro: 12.9 inch 2nd Gen

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Okay, well maybe you can't upload videos here. So, here's a Vimeo link to the Screen Recording.

iMac Pro (2017) Processor: 3GHz 10-Core Intel Xeon W / Memory: 64 GB 2666 MHz DDR4 / Graphics: Radeon Pro Vega 64 16 GB | iPad Pro: 12.9 inch 2nd Gen

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Hi deeland,

 

This is a bug in Global Colours - which explains why none of us were able to reproduce it! :) If you don't use a Global Colour, everything is fine and all numbers agree with themselves... It seems that Global Colours are doing (what appears to be) a default unprofiled conversion between colour formats and this is very easily fixed, but we weren't aware of that until now, sorry. We'll get that sorted - thanks for the report :)

 

Thanks,

Matt

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Hi Matt

 

Glad I can help. One thing I'm good at is finding bugs, much to my chagrin. I want to make clear, I'm not here to stir the pot, as I think you have some great products here. Anything I can do to help make your product better, I will do. My relationship with Adobe these days is such, that I can't be bothered reporting similar bugs in the software.

 

Back to the issue at hand, creating a Global Swatch was one way, and I happened to use it in the screen recording. However, I originally created a colour from the palette, and created a swatch there, too. Just did the same thing, and got differing values again, with what I assume is a non-global colour.

 

To be clear, how does one make a colour that is NOT global. Or, should I say, check that a swatch you've created is not global. Having checked the help section of AP, I'm not sure.

 

Also, as I said earlier, I found a similar issue in Affinity Designer. Consistent values in Sliders, not in Chooser, and different values to AP.

 

Dee

iMac Pro (2017) Processor: 3GHz 10-Core Intel Xeon W / Memory: 64 GB 2666 MHz DDR4 / Graphics: Radeon Pro Vega 64 16 GB | iPad Pro: 12.9 inch 2nd Gen

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