Preview resize images - quality

[hasole]

Hi

Does anyone know if you can change the quality of a resized image with Preview? I've created a service to resize images down to 800px width, but most of the time the file size is as large as the original. This is resizing screenshots off my mbp (1440x900 res)

Thanks

 

[miles01110]

I've created a service to resize images down to 800px width, but most of the time the file size is as large as the original. This is resizing screenshots off my mbp (1440x900 res)

...how is that even possible? If you resize something you change the file size by definition...

 

[GGJstudios]

Tools > Adjust Size:

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