Optimising Images for a Website

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JPEG versus PNG

Use JPEG for photographs and PNG for graphics. In other words, if the image has many colours, gradients and textures (e.g. a photograph of a landscape), use JPEG; if the image has sharp lines, clearly separating areas of relatively consistent colours (e.g. a basic logo), use PNG.

Compress Images

Install jpegoptm:

sudo pacman -S jpegoptim

Compress images by specifying the target output size:

jpegoptim --size=<TARGET_SIZE> <INPUT_FILE>

Strip Metadata

Install exiftool:

sudo pacman -S perl-image-exiftool

Strip metadata, but leave orientation information:

exiftool -all:all= -tagsfromfile @ -exif:Orientation ./*.jpg

To check what metadata is still present:

exiftool <img-name>.jpg