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Known Participant
April 5, 2023
Question

Incorrect file size showing in photoshop

  • April 5, 2023
  • 1 reply
  • 1530 views

Hi,
When previewing file size in photoshop (Image > Image Size), I see a different size from what shows when the JPG is then saved on my machine. Please see example below. Does anyone know why this is happening please?

Photoshop - 3MB

This very images saved on laptop - 596 KB

???

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1 reply

davescm
Community Expert
Community Expert
April 5, 2023

Image size shows file size in RAM so 1276 x 823 x 3 = 315044 = 3.0MB ( There are 1048576 bytes in a MB)

 

That is different to the saved file size on disk, after lossy jpeg compression which compresses the file to 596KB.

 

Dave

MargoM.Author
Known Participant
April 17, 2023

Hello Dave,
Thanks for the answer. Sorry if I'm asking silly questions, but what does the 3 in '1276 x 823 x 3' stand for? The 1276 and 823 are height and width in pixels, but I'd need help wrapping my head around that last componenet of the equasion 😄

davescm
Community Expert
Community Expert
April 17, 2023

The three is three bytes, one for each RGB colour in an 8 bits/channel image. If the document was 16 bits/channel it would be two bytes per colour, so x 6.

Dave