CIELab - digits after decimal point

[Roughweiler]

Hi all together,

first of all i'am very impressed what kind of software the Affinity suite has become. I'm using the Adobe Apps very rarely by now (and when in the purpose to convert files).

But... there is one thing that's annoying me a little: Color values within the CIELab color space can't have a decimal point. I'm working with the HLC color referencing system very often, which is based upon L*a*b* values with one digit after the decimal point.

The problem is: none of the Affinity apps is providing an option to use L*a*b* values with a decimal point, just integers are available. Is there a chance to get this feature in the Affinity core?

Greetings from Germany,
Jens

[NotMyFault]

Hi Jens,

 

welcome to the forum. Could you explain in more detail in what context (in Affinity Apps) you are using L*a*b values?

It might look a bit strange, but actually all pixel color values are encoded and practically fixed decimals numbers.

The values are store as binary numbers from 0 to 255 (8 bit) or 0 to 36535 (16 bit), but you need to divide by the maximum value to get a normalized (effective) value between 0.0 and 1.0 (point or comma as seperator depends on regional settings)

In RGB, you get 0/255 to 255/255

In LAB, you have (color panel, and info panel / color sampler in LAB mode)

• L from 0.0 to 1.0, shown as 0 to 100
• and a/b from -1.0 to +1.0, shown as -128 to +127. 

You can use procedural texture filters to directly access the numeric color values (as 0.0 to 1.0, so you need to normalise them again to match what the color panel shows).

It is unfortunate that Affinity does not provide an UI to enter colors in full resolution, only RGB allows to switch to 16 bit and enter RAW binary numbers. You may use this as workaround to indirectly enter LAB colors as sRGB, using external conversion tools.

Internally, Affinity use the full 16 bit resolution to calculate all color values in LAB mode.

As a complex workaround, you could use a PT filter to render a given LAB color (entered as binary values and converted accordingly). Then use the color picker in LAB mode to set the actual color.

 

Another trick:

Some sliders show 0-100, even when you can enter 255 different values. You can use ALT key and mouse wheel to adjust the value to the next lower or higher value (e.g. 50 means 127/255, and you can achieve 126/255 and 128/255, both still shown as 50 in the slider. But the info panel will show changes of color.

 

 

 

LAB color setter.afphoto