Understanding PSD filesize

[danezeq]

i don't get something: my psd file are always so heavy.

When i drag a 2MB jpg file intoshotoshop, do nothing to the file and just save it on psd, it size will change to 20MB+

If i'll add linked file (LINKED, which means the data stores elsewhere!) then the psd size will change to 45MB+

What am i missing? how can i reduce the psd files size?

Thanks 🙂

[TheDigitalDog]

JPEG is highly compressed and 8-bit per color. PSD isn't compressed and may be higher bit depth. 

See; https://www.adobe.com/creativecloud/file-types/image/raster/jpeg-file.html

And really, you probably don't want to be dealing with PSDs and instead TIFFs which can under go (lesser) compression if size is really a factor to you:

http://digitaldog.net/files/TIFFvsPSD.pdf

[D Fosse]

A lot of peple think jpeg file sizes are "normal", but they're not. Jpeg uses very aggressive data compression to reduce sizes down to perhaps 2-10% of native size - but at a price! The compression is destructive, non-reversible and cumulative. Don't resave a jpeg if you can avoid it.

An uncompressed PSD or TIFF is the real, native file size, counted as bits per color component per pixel.

When you open a jpeg it is decompressed back to its native size, many times the size on disk. In fact, an open file doesn't even have a file format. File formats are recipes for packaging into a storage container. Jpeg packaging picks the file apart in a way that can't be fully restored.

With a linked file, you still need a full size preview. So in your case that's 20 MB alone. In addition, smart objects have a bit of overhead.

[MarekMularczyk]

When you import/add a JPEG into your document, JPEG being a highly compressed file is decompressed and becomes a much bigger file and that's why your PSD is much bigger as PSD is a full size file.

Try to open a jpeg in Photoshop and check the file size/compare to original (you can see the file size of opened jpeg in the bottom left corner of your document window).

[danezeq]

Thanks for all answer.

So is there anyway to add layers to jpg file, save it compressed but not flattened, and open it again later, edit the layers and save it again as editable file?

[c.pfaffenbichler]

»So is there anyway to add layers to jpg file, save it compressed but not flattened, and open it again later«

Technically speaking psd by default employs compression anyway, but lossless compression, so the compression results are not as steep. 

Each time jpg compression is applied damage is done to the image, so fortunately there are no layered jpg-images. 

[danezeq]

Okay i see

 So is there any way to "strenthen" the psd compress?

[c.pfaffenbichler]

No. 

But to make sure check if Photoshop > Preferences > File Handling > Disable Compression of PSD and PSB Files is unchecked. 

[Stephen Marsh]

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danezeq wrote:

Okay i see

 So is there any way to "strenthen" the psd compress?

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PSD compression can only be disabled. You could try TIFF and compare LZW vs. ZIP compression for a layered file, it will depend upon image content on which compresses better (usually ZIP but it would likely be slower).

Photoshop PDF format supports layers and JPEG compression, if you really wanted them.

[danezeq]

Okay i saved as tiff and file went down from 46MB to 10.5MB!

that is something! thank you!

[Stephen Marsh]

A layered TIFF, yes? Are the layers there when you open it back into Photoshop?

[danezeq]

yes i checked this. the only layer a have still exist.