Ability to customize the behavior of Autocrop based on keystoning


(Greg) #1

Upon loading a JPEG image into PhotoLab (from a cell phone camera), I turned off auto Perspective correction and manually applied +20 to the up/down slider. (This turns the uncropped image into a trapezoid that is much wider at the bottom than the top.) In the Crop module, I set Correction to Auto based on keystoning… and Aspect ratio to Unconstrained. This yields a crop with the following dimensions:

5084 x 2973: 15,114,732 pixels

With the Crop tool enabled in the preview pane, I can see that the top few lines of the image have been cut by autocrop. This yields a slightly wider image, which I’m told is normal because auto crop mode gives preference to width when the image’s orientation is landscape. But the amount cropped from the top seems arbitrary - and I’m unable to see the practical value of doing this. When I manually adjust the crop by including the entire vertical range and trimming the left and right edges to fit within the trapezoid, I get a cropped image with these dimensions:

5076 x 3012: 15,288,912 pixels.

I would like to be able to tell the crop tool (in auto mode) to maximize image area, maximize height, maximize width, autoadjust manual overcropping, etc. Its default behavior (not a bug, per ticket #158773) when there are perspective adjustments can be much too arbitrary. Furthermore, it is presently difficult to accurately gauge the edge of the image in the crop tool for manual adjustment due to rendering bugs. (One must disengage the crop tool, zoom to 100%, and move the preview area to the corners to make sure that none of the black region beyond the image boundaries is showing.)