Improve quality JPG

[quand]

(05-04-2021, 03:43 PM)programmer_ceds Wrote:

(05-04-2021, 02:55 PM)quand Wrote: Hello

if i save a jpg image with an initial compression of 86 with a compression of 90, will i gain in quality? what happens if i do that?

many many thxxx

As I understand it JPEG compression works by saying that two colours that are very similar can be recorded as the same colour - thereby losing information. The lower the compression number the further apart colours can be and still be considered the same colour - thereby losing more information. Once the information has been lost there is (effectively) no way of getting it back.

Simply opening the image and resaving with a higher compression number should have no effect.

Unless it's an image of no importance then always keep a copy in a format that doesn't involve lossy compression - for instance tiff, xcf. Then edit this version, exporting to jpg when required.




okay, very well, please excuse my question which is that of the beginner that I am; in any case, I thank you.

Is it possible with Gimp to know at what level of compression a jpeg image taken from the internet has been saved?

thank you