Cropping images doubles or more the image file size, with default 90% quality setting

Hi,
I am using an image field for article and teaser images. Most of the cases I am putting optimized images in the needed size on the server.
Anyway, other users sometimes do not know, how crop images to the correct dimensions so I am using the options "copying original" and "cropping". I discovered that the cropping option increases the image file size enormously. The original file, as an example, is 78 kb and the cropped file results in 173 kb!
Rooney

i think you didn't have same compression level did you try to reduce it in field ? (ex 70)

Hmm. I can try, but still. The original is compressed. So it is the quality I want to have and if I set 70 % or whatever less the quality will go down for the large image thumb.
Rooney

Hello

some imaging software will achieve very good compression rates , much better than phpThumb and GD found in web server,

- you can make the image field use the original image as a specific size thumbnail without any resizing
this is a per small / medium / large image thumbnails setting

so you can enable this for: large thumbnails
parameter name is "Copy original *"

Yes. I know and I am using this setting. (I even thin it was me who requested that feature ). Problem is that some users do not exactly now how to size images with an image editor, so I use cropping to make sure that the images have the needed size.
Anyway, it is not a critical issue. I just thought that tripling the image weight was too much, but I understand that it is dependant on the web server software!
Rooney