I’ve been attempting to up-size a 90 x 40 cm image (= 12756 x 5669 pixels at 360 ppi) to 105 cm wide with constrained proportions (= 14882 x 6614 pixels).
Using a flattened 8 Bit source Tiff and entering these values into Size - Width and Height in A.I. Gigapixel, the created output image is 14882 x 7716 pixels. I’ve tried this a few times with the same change of aspect ratio.
Is this a bug? I still got a good result by re-sampling back to the correct image proportions in Photoshop, so I’m pleased with A.I. Gigapixel in general. I also notice some loss of contrast, saturation and sharpness in the output images but they are quite easy to restore in Photoshop or Studio.