Tring to find a good compressor for PSD files

[toi007]

once I saw a post in some forum about a guy who had more that 4 gigabytes of PSD adobe files and used mac

He used stuffit to compress it to a dvd but it couldnt get there and it was too slow
then he used dmg to compress and it was faster and possible
if he used some of dos and windows compressors it would be in a single file something like this...

I used only one file but it has some diferences acording to the inside information of PSD adobe photoshop file sometimes plzma and stuffit and 7z are better in this case the better one in size its fp8.exe and the king of speed is rar of course

but theres some math here included

if the guy had more than 4Gigabytes of compressed sitx than rar would be even bigger no matter the max speed
soo only compressors like 7z plzma or fp8 would be aplied

and if it was more than 7 Gigabytes sitx only fp8 would get there....


I do have to change a bit this first message by saying that im going to find some dmg compressor to compare it
if you know something a bout it it could help for xp or dos

[Black_Fox]

RAR is weak on PSDs because it has small dictionary and cannot "see" that there are similarities further apart (4MB dictionary is too small to detect that 8MB PSD is a doubled 4MB picture). I had made some comparison here (sorted by PSD compressed size ascending, compression/decompression speeds are on the right). Unfortunately there are mainly experimental compressors/archivers

[Skymmer]

I better would not trust the StuffIt's PSD compression. Official documentation clearly states:

Pixel-perfect

JPEG Lossless (.jls)
JPEG 2000 (.jls) Note - recompression is only applied when a j2k file is lossless encoded
GIF (.gif)
TIFF (.tif, .tiff) Note - Some are recompressed bit-perfectly, depending on how they were originally saved.
PSD (.psd) Note - Some are recompressed bit-perfectly, depending on how they were originally saved.
PNG (.png)
PICT (.pict, .pct)
PxM (.pbm, .pgm, .ppm) Note - Some are recompressed bit-perfectly, depending on how they were originally saved.
Zip (.zip, .cbz, .docx, .xlsx, .pptx, .odt, .odg, .ods, .odb)
PDF (.pdf)

[Piotr Tarsa]

I think there's switch to control the lossiness of compression.

[maadjordan]

I've been using Stuffit for a while now over many PSd Tiff and not all is preprocessed and few differ from original but content is same but data order is a bit different.