Grid pattern appearing in grain when exporting in jpg

Hi @carter.c,

Thanks for sharing the comparison images. The grid artifact in the grain is visible in the JPG Large export. This points more toward the JPEG export/rendering pipeline itself rather than the source scan or lens corrections. This might be expected JPEG compression behavior rather than a defect.

What you’re seeing is part of a known class of issues where JPEG compression artifacts interact with very high-frequency detail, such as strong pushed-film grain.

Under certain combinations of grain structure, output size, and compression quality, this can make JPEG block boundaries become visible as a faint grid pattern within the grain itself.

A few likely contributors here:

• JPEG compression works internally in 8×8 pixel blocks

* With pronounced, uniform grain, those block boundaries can become visible

• The resizing/downsampling applied by the “Large” preset can sometimes align poorly with the grain frequency and exaggerate the pattern further

A few things you can try without applying noise reduction:

• Export JPG at Quality 70-90. Ensure "Output Sharpening" is OFF.

• Try exporting as TIFF or PNG. To verify that the artifact disappears completely without JPEG compression.

• Export at full resolution and resize externally afterward. For example via Photoshop using Bicubic Sharper/Bicubic Automatic.

Let us know how it goes.

Best,

Anshul Saini