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Cake day: June 21st, 2023

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  • You can make nearly all images small enough to upload and still look good without dropping colour depth. There are 3 ways to achieve it basically:

    • Resize it to a lower resolution (1280 x whatever looks just fine on a screen)
    • Reduce the quality
    • Change to lossy (JPG) from non-lossy (PNG)

    The resizing is usually enough.

    The quality reduction is something that google pagespeed focuses on too. For most apps that means choosing a lower “quality” when converting to jpg or saving as a new jpg. 85% of original is good.

    If you happen to have imagemagick installed, I have a little script that I use called “resize_to_pagespeed.sh”. The jist of it is this:

    convert inputfile.jpg -filter Lanczos -resize 1280x1280 -sampling-factor 4:2:0 -strip -quality 85 outputfile.jpg

    I just ran this on a 2.4MB photo (below) and it came out at 186KB. That’s a 13x reduction. Right click -> open in new tab to see it full size.

    If the image isn’t square, imagemagick is smart enough to figure out correct dimensions.