Running Version 1.5 of ZenCart, have only Image Handler V4 installed for photo maintenance with GD FreeType Version 2.3.7 (GD Version bundled (2.0.34 compatible)). Probably need to upgrade to the most recent sub-version; however, haven't seen in the documentation anything that indicates a potential upper limit on image dimensions. Others have commented either in this version or previous versions about how they have had to resize the image before presenting to IH4. I typically will ensure that the largest dimension of an image is 1280 pixels. Though some have been larger without issue, this seems to be about where the image can be displayed even in the small perspective. Otherwise, pages will not display that include the image (at any size) which is problematic also in the admin section.

Is this something that IH4 can not handle, is it related to GD, is it a combination of the two? When such an image is uploaded and causes problems, then if I disable IH4, I can go back and address the image (remove, replace, etc...); however, I can't seem to remember having seen anything documenting the upper limits of an image.