How to resize a bulk of images?


after adding many images (4 MB each) to my cards, syncing has become slow.
Is there any procedure or app to reduce the size of a bulk of images (all in the same field) in one stroke?
What is the recommended size?
At moment I am using Anki on PC, Ankiweb and Ankidroid simultanously which is possible with the aid of the nice app “image style editor”.

Best regards

All media files are stored in the same location. You can use an external tool like Irfanview to edit them in bulk.
There is not a recommended size as that depends on your card design. Maybe the images are larger than you need, then you can scale them down. Maybe they are PNGs, but you don’t need transparency etc., then you can convert them to JPG and adjust the quality.

Image Style Editor scales your images using CSS, which doesn’t alter the source images. If you scale down the source images as described above, you’ll probably need to redo your adjustments with this add-on to keep the currently displayed sizes.


I would mostly say what @Rumo has put, but would recommend pinga. Image compression goes very deep, and the best tools like Zopfli arn’t worth learning for casual use. JPG/JPEG will likely be better for photos, but I have seen many decks optimized for SVG, PNG or GIF formats that would be bigger if you bulk converted everything.

The optimizer tool that pinga uses is well established (pingo) but the simple drag and drop version is fairly new, so it recommends having a backup.


Problem solved.

I could resize all images to jpg-format very easily with the aid of

Thank for your help!