Legacy ImageMagick Discussions Archive

When I create a PSD file with IM with the following command:
open it in Photoshop, and save it (no editing), the PSD file ends up approx 30% of the size that IM created. Why the difference? How can I accomplish the same with IM? Ie, create a PSD file that's a lot smaller using the same images?
The first 2 images I use are png's because they have transparent pixels (in fact, most of the two images are transparent, and basically contain a border only), the jpg is a photo.
Cheers!

IM has a "-compress ABC" setting. However, the only setting that affects the size of PSD files is "RLE" or "RunlengthEncoded". This shrinks graphics files, but makes photographs larger.

I am working on adding support for writing zip compressed layers. This might also reduce the size of the file.

So does Photoshop compress (does it use zip?) layers? The difference is significant; if I create a PSD with IM from 2 PNGs and one JPG where the PNGs are basically 3 color images (white, red and transparent) and the JPG is a photo, I end up with a PSD size of 140MB or so. If I create a PSD of just the JPG (which is a 98% compression Jpeg of around 6MB) I end up with a 34MB PSD.
If I load the PSD consisting out of the 2 PNGs and JPG in Photoshop, and then save it (without editing anything), I end up with a resulting PSD of around 40MB. Still big, but a far cry from 140MB.
If PS does use zip to compress layers, then having zip as an option in IM would be awesome.
Not a big issue at the moment for me, and it's good to know it is likely to be implemented in the future.

I'll have a play with that and see what the impact is.

snibgo wrote:IM has a "-compress ABC" setting. However, the only setting that affects the size of PSD files is "RLE" or "RunlengthEncoded". This shrinks graphics files, but makes photographs larger.