save image - compression means?

when you are rendering, eg in png, there is a setting for compression. it goes from 0-100%. what is this percentage, is it the percentage of compression - where 100% should be nothing left of the image, or percentage of the maximum compression, or is it the inverse where 100% is uncompressed? png is supposed to be lossless, is that really true?

Which to use for rendering to image sequence before making a movie in the VSE?


With lossless image formats such as png. The compression value will try to compress the image using more aggressive compression techniques but it will NOT alter the visual output of the image. This means that it can take slightly longer to compress large lossless images such as png so its an option to alter the compressive amount even though the resulting output image data will still be identical to the original image (just the file size changes).

With lossy image formats (such as jpg). The compression value will alter the original image output data and you will get artefacts if you set the compressive to high.