*Edit: Just learned that I’m not the first person to figure this out. @Duckling has a thread detailing how to do this directly from a mobile device here!
Hi, everyone! I know a lot of creators have been complaining about the forums adding white backgrounds to their once transparent images. I’ve been uploading my work for several weeks now and believe I have come across a fix to this.
Step 1
If you edit on your phone like me, transfer your PNG images to your computer and run them through your preferred compressing website so the requester will be able to upload them to their gallery. I use Resize Pixel’s compression tool.
Step 2
This tool is great for uploading to the gallery; just set the compression to something slightly under 1MB like 950 KB, and you’re golden. But when uploading to the forums, most times I will be greeted with this code:
^Note the ending extension: .jpeg
Now, in my files, this is a PNG image:
Yet somehow the forums has converted it to a .jpeg file which, unlike a .png, file has a background.
Step 3
When I first noticed this, I tried to edit the code directly which did not work. I then thought: “Maybe it has to do with the size of the image?” So I ran it through the same compressor again which did not alter the size any ://
After that, I came across the website Image Diamond. This website does a great job of heavily compressing images w/out losing their quality, and I do not believe there is a daily limit like other similar free websites (there is a 5 mb limit per file, though, but since we already compressed our images to 1 mb, we don’t need to worry about that). So I popped my once-compressed file into here and compressed it again. Upload your twice-compressed image into the forum and note the ending extension now:
Yay, cool, it’s .png now! And if you look in the previewer on the right, it should indeed be transparent:
Lol, it’s a little convoluted and maybe there’s an easier way to get the same result, but this is what’s worked for me each time so far. If two compressions don’t work, try three. I’ve never had to do more than that. Next time you need to upload a transparent image to the forums, let me know if this method works for you :))
Thanks so much for sharing this 
This is exactly what I needed to know ~ 
