I am trying to resize the jpg image using Preview but upon opening up the image (tools --> adjust file size) without changing any image dimension or resolution the file size was already dropped (e.g., from 4.6 MB to 1.7 MB). Then if I change the dimension of the image the file size dropped down to just couple hundreds KB. I've never had this problem before with my other Macbook (older OS). Can anyone help?
MacBook Pro, OS X Mountain Lion (10.8.3)
I'm not seeing that problem. When I open an image in Preview ad go the the Adjust Size tool the Resulting size box shows the original size of the image
When you first open the file is the Resulting Size box showing 100%?
Are you sure you are opening the actual image and not a thumbnail of the image?
I'm pretty sure I opened up the full size image then go to Adust Size Tool.
This is how it looks on my macpro. If I adjust the dimension, say to 950 px width, the resulting size will become 150-yish kb.
I don't have this problem with my macbook white (forgot the version but it's pretty older os).
The resulting file size displayed in your screen shot is not only a reflection of the pixel dimensions, it also is changed by the amount of jpeg compression that is applied (by Preview) to the file.
So in your case, Preview is applying a greater amount of jpeg compression than was used in the creation of the original document, so the file size is/will be smaller.
Here is an example of the opposite happening: I am opening a 1.2 MB jpg file, Preview says it is going to be 1.5 MB, as the level of compression to be applied is less than the original, so Preview is creating a larger file size:
To avoid or mitigate this, instead of saving your work after your pixel size adjustment, Export it instead and use the Quality paddle to adjust the jpeg compression to best - which will result in the largest file size.
MtD
It still gives me the same result. When I resized the dimension to 985 px width, the file size dropped to 138KB and when I exported it the file size of the image remains at 138 kb. With this new preview that comes with OS 10.8.3 I can't even save the image. The only option is to export the image.
Is there a way to change the level of jpg compression in preview?
This....
westie_54 wrote:
Is there a way to change the level of jpg compression in preview?
I do not know - but are you thinking that reducing the file pixel count from -
3888 x 2592 = 10077696 pixels
to
985 x 657 = 647145 pixles
shouldn't reduce the file size?
MtD
What happens if you uncheck Resample image?
Image file size reduced drastically in preview
