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Jessie844

: Size of PSD in CMYK increases trifold after adding a photo I have a 8640x12120px poster template in PSD. It is in CMYK and has a size of 120 MB. After pasting a 8640x4790px 4MB JPEG photo,

@Jessie844

Posted in: #AdobePhotoshop #Cmyk #FileSize

I have a 8640x12120px poster template in PSD. It is in CMYK and has a size of 120 MB.

After pasting a 8640x4790px 4MB JPEG photo, the size of PSD file increases to 350 MB. Is there a way to avoid this and keep the size closer to the sum of originals?

Update: I tested it from scratch by pasting another 4000x3000px 4.5 MB JPG photo to a new empty 8000x12000px 7 MB PSD (CMYK/8). The PSD's size instantly increased to 104 MB. Using "Place" option instead of pasting produces 108 MB PSD.

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@Angela777

I'll preface this by saying that you still haven't provided enough information about the before and after files for me to be certain of any answer. Ideally, showing the composition of layers and their properties would help a lot.

You also haven't expressed your understanding of jpeg compression so I don't know if my answer is repeating information you already know. Nonetheless, I hope it's useful:

Edit: I'm just after seeing your answer to a separate question on png files, it appears that you're likely familiar with everything I describe below, which means I may have guessed the missing details of your question wrong. I'll leave it incase it's useful for anybody else as it's still relevant to the current details should anyone be searching for the same question.

I have a hunch that this is down to confusion over how various files (PSDs and JPEGs) store their information.

JPEG

Jpegs shrink the filesize of images by lossy compression, meaning that if you have an image that's 10 pixels by 10 pixels, it can save it in a filesize smaller than it would have typically taken to store what those 100 pixels were, but that the 100 pixels would't be identical to the originals. Hence, lossy. It's advantage is that we can't, typically, perceieve that they're different with our eyes. The more compression you use, the more likely we are to perceive it.

PSD

PhotoShop PSDs also use compression to shrink filesize but, conversely, it's lossless - meaning that whatever tricks it uses to shrink the filesize of 10 pixels by 10 pixels, the resulting 100 pixels will be identical to the original 100 pixels.

This has an advantage in image data integrity. You will likely be editing the images and want to know each save and open of the file is exactly as you left it.

The disadvantage is that this type of compression doesn't produce as drastic a reduction in file sizes as JPEG.

Saving JPEGs as PSDs

If you have a PSD open in PhotoShop at 10 pixels by 10 pixels, you can bring a JPEG into the software by any means (placing, copying and pasting, etc.) but once it's saved, the 100 pixels of JPEG information are saved using the PSD compression technique instead. They are now just 100 pixels, not a JPEGs impression of 100 pixels. The filesize will likely go up.

But how does the filesize stay down on massive layers of pure colour or large areas of colour?

This is one area that PSD compression is good at. Shrinking the filesize dramatically on areas of the same colour. So blank layers and white layers of any dimensions will have a very small file size. Introduce a photograph or drawing as another layer (or in place of that layer) and the PSD can no longer see lots of the same colour next to each other and can't hope to keep the file size nearly as small when it tries to compress.

Pixel Previews

It's worth knowing that for speed of editing and previewing, PhotoShop also saves a hidden preview layer of each layer in your PSD at 1:1 pixels. This little known piece of information answers a lot of confusion about ballooning filesizes and frustrations as to how smart objects and copies of smart objects can see file sizes increase against the belief of how they're expected to work. I digress, but it's related to the subject and useful to know.

If the information here was all already known to you or is way off the problem, I'd suggest editing the question to include a lot more information about the before and after files.

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