Ever wonder nowadays why website use a full background image , but so light in size?
If you notice on the type of picture, it’s jpeg.
the reason is only this type that supports, scale down Pixel per inch. an article suggest 72 to have it lower down to be viewable on monitor only, not for printing.
and jpeg support compression that is by default 8x8 pixels and selectively reduce the detail within each block. the higher compression ratio block pattern becomes more visible.
The pattern in the image also effect how the compression would be come. more color and gradient will result in more “pixelate”.
Anyway i found this software Jpeg compression really do the job.