Here are some ideas for improving the Seamcarve filter:
It would be great if the user could choose colours for marking the parts to be preserved/removed. If the part of the image I want to be preserved is green, using green as an indicator isn’t exactly helpful. Same with red for removal.
More importantly, it would be really useful if G’MIC enabled users to insert the new size not just in %, but also in pixels or other units. Since I’m coming from print publishing, one major reason to use a seam carving feature is to enlarge, for instance, an image that spreads over one and a half columns of text in a print layout to two columns, or to scale it down, so it only has the width of one text column. The width is known in pt, px, mm or inch, so percentages are not really helpful unless you also use a calculator.
One particular feature of the Liquid Rescale plug-in for GIMP is missing in G’MIC, namely scaling down, removing items and then scale back to the original size.
In Photoshop there’s an interesting option to determine the direction of the image expansion/shrinking, i.e. not only from the centre, but also from left to right, right to left, top to bottom, and bottom to top, as well as each corner of an image.
The behaviour of spin boxes in this dialog (and maybe others) is a bit odd, because a click changes the percentage in increments of 2. Is this a bug in G’MIC, Qt – or even intentional?