Photoshop file too big - 1,8 GB

Thank you all for your replies...I will try to look over this and see what from it I can understand and use. Thank you. 

Should we assume this is actual wallpaper for interior room decoration, not “wallpaper” in the sense of a background for a computer or phone screen?

If it’s room wallpaper, you may be able to save a lot of space by working at 8 bits per channel, because I am not sure that a CMYK wallpaper printer can actually reproduce the potential quality of a 16 bits per channel image.

It might also be possible to save space by working at a lower pixels per inch resolution than 319ppi, again because a CMYK wallpaper printer probably isn’t reproducing detail that fine. But whether changing the resolution is an option depends on how much the 50 x 60 cm document needs to be scaled to its final size as a repeatable tile for a roll of wallpaper.

Now, if it is meant to be computer “wallpaper” then it only needs to be as many pixels as the screen, like a 4K display would only need a 3840 x 2160 px image to fill the whole screen.

@kristinaplasgard 

50 x 60 centimeters is approximately 20 x 24 inches. Bert Monroy's Times Square has over 500,000 layers, measures 300 in x 60 in, weighs 6.52 GB (flattened), and took four years to create.

You might want to check out some of his techniques on YouTube and in LinkedIn Learning.

• https://www.youtube.com/playlist?list=PLtWJCzi3h2Hwhx5IbRIkciJVolwEu6zYD
• https://www.linkedin.com/learning/creative-inspirations-bert-monroy-digital-painter-and-illustrator/times-square-project-overview

In addition, four channels (CMYK) creates a much larger file than three channels (RGB).

Jane

In addition to the previous replies, ask yourself what are you really gaining with 16 bpc and CMYK – apart from the added file sizes. If you have to make sacrifices to reduce size, I would go for 8 bpc and RGB before sacrificing layers, but that is just me.

Also don't discount the impact of bloated metadata:

https://prepression.blogspot.com/2017/06/metadata-bloat-photoshopdocumentancestors.html

There could be data outside the canvas boundary. That will quickly blow up the file size. If there is and you don't need it, select all > crop.

Just to get a baseline, make a copy of the file and flatten it. A flat 16 bit CMYK at 6280 x 7535 pixels will be about 372 MB uncompressed.

A pixel is a pixel; it takes up a certain number of bytes per layer. I don't know what "a lot of layers" means, but it could easily reach 1.8 GB.

That does not seem an unreasonable size for a multi-layer 16 bit/channel CMYK file at that size. Remember that is a master file, you would never send it onward. For that you would use a flattened copy.

You can check your Preferences File Handling settings.
If Disable Compression of PSD and PSB files is unchecked, the files on disk will be smaller but save and load times will be much slower.
If Maximise PSD and PSB File compatibility is Never then again teh file will be smaller, as a flattened version will not be included in the file, but it will not be read by applications that use that flattened version such as Lightroom.

Dave