PNG vs PSD

[gwpriester]

I had an interesting experience recently and I am hoping someone might have some insights.

I was trying to save a custom stereogram that is approximately 36" x 24" at 300dpi out of Stereogram Generator, the software I use to compile my stereogram images.

Normally I save to PNG but I kept getting Out of Memory errors.

I finally decided to try another file format and picked Photoshop PSD. Not only did the image save, it saved almost instantly even though the file size is 191 MB! I was able to save one PNG version but it took about 30 seconds and the file size was about 51 MB.

Does the PNG format because of its file compression method require more system memory to compress the image?

[handrawn]

the reason the PSD saved 'alomost instantly' is because it is not compressed; that's what makes a PNG take longer, and it's quite possible that the compression process has an additional memory overhead

[Cloud]

PNG files take longer to save due to the compression method they use (zip) the following link to the photoshop forum explains:

http://feedback.photoshop.com/photos...o_long_to_save

I have noticed when saving a png file in photoshop it does seem to take as long as saving a tiff or sometimes longer but resulting in a smaller file size

[handrawn]

compression time also depends on complexity - a PNG with a monochrome background will compress faster than one with a textured background for example..

[Soquili]

If you have multiple cores and the compression process creates multiple threads on each core it can consume a lot of resources.

[MarcT]

I imagine it's how the program handles this process.

Photoshop takes longer to generate PNG than Xara because it's compression settings are at maximum.
Also illustrator often chokes on generating moderate sized PSD and gives an out of memory error.

I always use PNG in between programs, the alpha support and compression is very convenient.

Marc