Ploblems with export

[Heikki Salonsaari]

Why export doesn't take the brightness of the image properly.

On the left is a screenshot of the Affinity Photo screen and on the right is the same image exported

[NotMyFault]

Hi,

 

your screenshot shows you are using RGB/32, with is (intentianally) using a linear curve to transform pixel brightness into display brightness. Handling a linear tone curve introduces additional complexity, which can be simply avoided by converting to RGB/16, and choosing an appropriate color space (RGB, ARGB, P3, ...). RGB/16 and RGB/8 will use a gamma curve to transform pixel brightness into display brightness, a model witch better matches the percieved brightness by humans.

If you want to export as jpeg, which only supports 8 bit color depth with gamma tone curve, it ill be much easier for you working in RGB/16 and getting predictable results, avoiding the issue you observed.

The export from RGB/32 to RGB/8 will definitely loose some color details, and dynamic range. To preserve the HDR dynamic range, you would need to export to HEIF (12 bit) or TIFF/PMG (16-bit).

For camera images, even with HDR stacking, you practically never exceed 16 bit dynamic range, so RGB/16 is good enough as editing format.

For RGB/8, you may need to tone map the images to compress the dynamic range into this limited range, or shadows and/or highlights will be lost.