>>588268This happens because AnimePaper adds html advertisements at the end of the image data, which 4chan thinks is javascript shit in some cases.
1. Open image in windows fax- and picture viewer
2. Click the little disk icon at the bottom
3. Select "PNG" as file format
4. Save somewhere, then upload that instead
If it still doesn't work, save as .bmp first, then open the .bmp image and save that as .png and post that.