How to put JPEGs on a diet?

[yogiyang]

Hello,

I have a collection of around 10k photos snapped in various Mega Pixels starting at 4 mp to 16 mp.

I also have a few 300 dpi images that are created using professional image editors like Photoshop.

The file are mostly in .jpg format. But their sizes are quite large. Say for example some files are as big as 45 MB and above.

I want put all these JPEGs on a diet without any visible quality loss and resolution loss.

I tried to use IM for this but could not get much size reduction.

How can I get IM to reduce the file size without changing an image's size (dimensions), resolution (dpi) and color mode (RGB).

TIA

Yogi Yang

[snibgo]

Changing resolution (dpi) will make no difference to the size in bytes.

If you don't want to reduce the number of pixels, try this:

Code: Select all

convert in.jpg -quality 2 out.jpg

This will be small, but horrible quality. Pick a number closer to 100 for better quality but larger.

[yogiyang]

Thanks Snibgo.

I have already tried that out. The output looks really very bad when compared to original.

What I want to achieve is without visible quality loss also.

TIA

Yogi Yang

[snibgo]

You can start at "-quality 2" and increase the number until you can't see any visible quality loss. Or start at 100 and work down until quality loss becomes visible.