The discussion start on Community Central (here). The OP of that thread claims they are getting an error when they try to start a thread here. As such, I am starting the thread and we will see if the OP is able to post the details as a reply. If not, I will edit this post to summarize the situation.
me didn't quite understand what op waiting for. on the sample that was provided by the op, are different (by form, which is important) images. those images can't be simply cropped by some hard-coded coords.
in order to focus on the valuable part of the image, software have to:
decide what part is most valuable
define range of the valuable part
then crop out other parts
when 3 can be done simply, 1 and 2 are complicated. may be too complicated for non-commercial solution (me didn't see one so far).
I probably should have noticed this earlier, but if you want to stick with using gallery tags (which will make the page markup simpler), then I believe you will have to use JS. If you are willing to hotink the images, you could use Vignette to do the cropping. I had previously started on a template for this but haven't finished it yet. The downside to hotlinkingis they won't register in the system of places where the images are used. As such, the images may appear to be unused when they actually are being used.
In that case, you may want to ask for help here. Although I have some idea of what the JS would do, I am not sure on how to implement part of it. If needed, I can provide the general procedure I have in mind but chances are whoever helps you there will be able to come up with something similar.
I know little to no JS but what I am trying to achieve is cropping out the white in some of my images in some of my galleries, one of my galleries.
Any help would be appreciated, thank you in advance.
Well, as Fngplg said (and as I briefly mentioned on Community Central), it is more or less impossible to do this if the images are not of a uniform layout. By uniform layout, I mean that they are all the same dimensions with the object of interest in the same region of the image. From what Fngplg posted (I haven't checked myself), it sounds like your images are all different sizes. At the very least you would need to resize and re-upload them.