Problem summary Blur applied by the Bokeh node appears to have a size limit (in pixels). This means that for larger resolution images, the largest achievable blur will be smaller in relation to the image size.
Customer reported version Nuke 14.1v5
Customer reported platform
Steps to reproduce
1) Open Nuke.
2) Open the attached .nk script. The script contains the following nodes:
The left branch applies Bokeh to a 4K (4096x3072) Noise.
The right branch first Reformats the Noise by a scale of 0.5, then applies the same Bokeh, before reformatting it again by a scale of 2.
3) Ensure that both the Focal Length knobs on both the Bokeh1 and Bokeh2 nodes are set to 50.
4) Compare the output of the Bokeh1 node and the Reformat2 node. They should look identical.
5) Now set the Focal Length knobs on both the Bokeh1 and Bokeh2 nodes to 60, or higher. The images will no longer look identical.
NOTE: Similar behaviour can be seen when changing the Viewer's downrez settings, instead of Reformatting the image.
Expected behaviour
The output of both branches should be the same.
Actual behaviour In this script, it seems that the limit for the blur size was reached on the 4K image (the left branch in the script). Whereas reformatting the image to 2K, applying the Bokeh, and reformatting back to 4K allows a much larger blur size to be achieved.
Workaround Unknown.
Reproduced by support This bug has been reproduced in: Nuke 15.1v4 - Windows 11 - Linux Rocky 9 Nuke 13.2v6 - Windows 11 - Linux CentOS 7
Earliest version tested Nuke 13.2v6 - The Bokeh node did not exist before this version
