PSD file size puzzle

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  • Updated 1 year ago

If I open a 24MP raw image in ACR, open in PS as a Smart Object, the PSD is ~ 263MB.

If I open the same raw image in ACR, open in PS as an Image, then convert layer to a Smart Object, the PSD is 474 MB.

No real problem here, just curious about the size difference.

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Robert Stone

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Posted 1 year ago

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Max Johnson, Champion

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A smart object is a reference to another file... In this case that file is embedded directly inside your document like it was in a zip file... So with that in mind, when you convert to a smart object you are making a copy and saving it inside your psd... Then making a rendered copy of that file in your layer, duplicating your image.

That said, I would check if both your test files are set at the same color depth.
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Mark Heaps, Champion

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I know Smart Objects can either be embedded or they can be linked to source data. I wonder if the smaller file size that contains the raw data is linked?

https://helpx.adobe.com/photoshop/how-to/photoshop-linked-smart-objects.html
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Max Johnson, Champion

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I suspect the Open-As-Smart-Object is creating a new photoshop file at 8 or 16-bit depth with the 24-bit ACR embedded, while the Open then convert to smart object method is creating a 24-bit PSD with a 24-bit smart-object. Can't confirm here though.
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Robert Stone

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I think you are right. A raw file will contain 16 bits of data for each photo-site, while the image contains 3*16 bits (RGB) per pixel. The de-mosaic process would produce one pixel per photo-site. So the smart object for a raw much smaller. Thanks!