Gigapixel grid pattern artifact

I just installed the latest Gigapixel update v 3.0.5.

I want to use the GPU processing because it is quicker than the CPU processing, but I keep finding a pattern of visible line segment artifacts in the images produced with the GPU.

For example; Today I prepared a 1200 x 1800 pixel, 0,0,0 black, 16bit SRGB .tif file and had GigaPixel enlarge it 4x. The resulting file displayed soft white line segments that were spaced across the canvas at horizontal and vertical intervals.

I used a levels adjustment to exaggerate the appearance of the lines, and a more evident pattern emerged as I did so. The enlargement should be a solid black panel, but it is not. Finally, I crushed the levels range by dragging the sliders over to the far left and found this distinct pattern buried in the depths of the black:


I then ran the enlargement process with the CPU. I could not discern any of the line segment artifacts in the resulting image, but after I crushed the level range the same way I did with the the GPU example, I found a familiar pattern baked into the depths of the black:


Here are further enlarged crops of the two examples shown above:

GPU cropped and zoomed:

CPU cropped and zoomed:

I am generally enthused about Gigapixel up sizing but this unexpected form of digital watermarking undermines my confidence in using it to prepare a large scale master file.

I hope Topaz addresses this issue and continues to improve Gigapixel.

Topaz Studio Ver: 3.0.5
Operating System: Windows 7 SP 1 (6.1)
Graphics Hardware: Intel® HD Graphics 4600
OpenGL Driver: 3.3.0 - Build
CPU RAM (MB): 16140
VRAM [Total, Used] (MB): 1500, 1024
Preview Limit (Pixels): 3135

Thank you for your post. We are aware of an issue with these types of grid/block based artifacts and are actively working on an update to resolve this and increase overall quality. The latest update 3.1.0 that is currently available in beta does not address this, however a subsequent update will in the near future.