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Colour Depth Options


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If I have an 8 bit RGB document each channel is 2^8  bit or representing shade values 0-255.

now a 16 bit RGB each channel 2^16 bit or representing shade values 0-65535 per channel

So if I convert an 8 bit colour document to 16 bit I should have more colour options, but the colour sliders seem to be limited to the same 0-255 RGB vales or 00-FF Hex per channel, so it appears no increase in colour depth by converting document from 8-16 bit. Why is this?

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Hi @Affinity Rat,

Affinity will show colour values between 0 and 255 per channel in the Colour panels regardless if the image being edited has 8, 16 or 32bit colour depth, this is to simplify things from a user and UI perspective, the final image output will still be 16 bit as internal calculations will take place to convert the image to a 16 bit colour space.

I've provided a link below which goes into a lot more detail on this topic, it is referencing Photoshop but the same logic applies to Affinity.

https://www.quora.com/When-editing-in-RGB-16-bit-mode-in-Photoshop-why-are-colours-represented-by-8-bit-0-255-values-instead-of-16-bit-0-65-535-values

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Thank you Nathan, I presume that means the 8 bit colour reprentation in the colour palette will not represent the channel actually used in creating the composite image. 

So if the eyedropper is used to add a colour to the colour palette channel is an approximation of what the actual value is? (Since limited to 8 bit, but the image colour rez > 8 bit) So if you search for a colour with the colour selection tool, with the resultant selection (tolerance set to 0) the selection can contain more that one colour (in 16 bit image) since the palette doesnt have the ability to differentiate and display this level of colour resolution.

 

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As far as I'm aware there isn't a way to change the Colour panel to 16 bit on iPad, there isn't a reference to a configurable setting within the iPad versions of the guides for the colour panel, so this would limit you to only selecting the 8 bit colour values as an approximation.

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1 hour ago, Affinity Rat said:

It just occurred to me as I was using it, how does color rez work with limited 8 bits of shading, it didnt make sense to me. 😊

The usage of high color bit depth shines in different situations:

  • adjustments and filters won’t run immediately into banding
  • Digital photography has more reserve for color manipulation, e.g. boosting shadows
  • for painting / manually selecting colors, 8 bit are enough in most cases.

Affinity unfortunately has some nasty limits:

  • Unfortunately, Affinity uses forced 8-bit dithering when using gradients. This makes 16 bit mostly useless for gradients, as it impacts the actual image data. You can use advanced methods like procedural texture filters which fully support 16 bit.
  • Affinity is unable to render 16 bit color depth on screen for RGB/16 documents. It can create and store such files, but it renders in 8 bit only while editing.

Mac mini M1 A2348 | Windows 10 - AMD Ryzen 9 5900x - 32 GB RAM - Nvidia GTX 1080

LG34WK950U-W, calibrated to DCI-P3 with LG Calibration Studio / Spider 5

iPad Air Gen 5 (2022) A2589

Special interest into procedural texture filter, edit alpha channel, RGB/16 and RGB/32 color formats, stacking, finding root causes for misbehaving files, finding creative solutions for unsolvable tasks, finding bugs in Apps.

 

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8 hours ago, NotMyFault said:

Affinity is unable to render 16 bit color depth on screen for RGB/16 documents. It can create and store such files, but it renders in 8 bit only while editing.

I assume you dont mean using the desktop 16 bit colour option, but only the default 8 bit colour option on a 16 bit colour image.

 

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3 hours ago, Affinity Rat said:

I assume you dont mean using the desktop 16 bit colour option, but only the default 8 bit colour option on a 16 bit colour image.

 

I’m referring to this bug report (Affecting all platforms, desktop and iPad)

 

Mac mini M1 A2348 | Windows 10 - AMD Ryzen 9 5900x - 32 GB RAM - Nvidia GTX 1080

LG34WK950U-W, calibrated to DCI-P3 with LG Calibration Studio / Spider 5

iPad Air Gen 5 (2022) A2589

Special interest into procedural texture filter, edit alpha channel, RGB/16 and RGB/32 color formats, stacking, finding root causes for misbehaving files, finding creative solutions for unsolvable tasks, finding bugs in Apps.

 

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