Scope Panel stops working RBG/16

[NotMyFault]

Reported before, but got ignored.

Same issue in V2.

For documents in RGB/16 color depth, the scope panel stops to show any data if the alpha channel gets below 1/508.

steps to reproduce:

1. new document in RGB/16 color format
2. activate View>Studio>Scope

Last value where Scope shows data: alpha = 1/511

First value where Scope stops showing data: alpha = 1/512

 

bug scope panel stopps working for alpha 1 by 509.afphoto

[Chris B]

Hey NotMyFault,

Apologies if you posted this previously and it was missed. I hope that it was not intentionally ignored either. 

I'm just checking something with development before I reply and potentially embarrass myself. I'll get back to you as soon as I can as I'm not entirely sure what's going on with this one. 

[Chris B]

This is the reply I got from one of the developers:

Quote

For me the cut off is 510 vs 511, which makes some sense. I suspect that the document is rendered as RGB/8 for the Scope, even for RGB/16 documents, presumably for performance. Values are converted to [0,1] for use in procedural texture equations and afterwards converted back to [0,255] with rounding to the nearest integer, so any alpha value less than 1/510 will round to 0. Fully transparent pixels don't have reliable colour channels because the renderer assumes it doesn't need to render invisible pixels, again for performance, hence they need to be ignored by the Scope.

I hope that helps.

[NotMyFault]

Quote

For me the cut off is 510 vs 511, which makes some sense. I suspect that the document is rendered as RGB/8 for the Scope, even for RGB/16 documents, presumably for performance. Values are converted to [0,1] for use in procedural texture equations and afterwards converted back to [0,255] with rounding to the nearest integer, so any alpha value less than 1/510 will round to 0. Fully transparent pixels don't have reliable colour channels because the renderer assumes it doesn't need to render invisible pixels, again for performance, hence they need to be ignored by the Scope.

Hi Chris,

thank you reaching out to devs and clarification.

Unfortunately, this partially confirms my worst fears raised in another bug report: Affinity renders probably everything as RGB/8 for performance reasons, even in case of RGB/16 documents. I hope this will be fixed. Somedays.

See