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oliverm81709700
Participant
May 13, 2018
Answered

Problem with file size

  • May 13, 2018
  • 2 replies
  • 423 views

I have searched to know avail here for answers as to why photoshop is not showing me my image size in MB.  I am currently having to resize images for 500px and my website and it won't show me how any MB my file is.  Maybe I don't know how to read it but when I used photoshop on my laptop I was able to select image size and at the top left corner it would show me my file size in megabytes but now that I have a desktop it shows me in (M).  I don't even have a clue as to what (M) is short for, because if I export an image to my desktop it shows me in MB and it is completely different from what is written on photoshop.  Here is an example.  I exported an image and used the get info from the right click on my Mac and the image size stated it was 35.8 MB and then I opened it in photoshop and it stated it was 227.0M.  Now this is a problem because I don't know how to convert that to MB and size my image so it can be uploaded online. 

Sorry for the rambling, but any help would be greatly appreciated.

This topic has been closed for replies.
Correct answer D Fosse

That sounds like normal jpeg data compression. When you open a jpeg it is decompressed and essentially stops being a jpeg - when open it's just a pixel array like any other.

It only becomes a jpeg the moment you save it to disk, and then the jpeg format uses very aggressive data compression to reduce storage file size.

If you need a certain target file size for web, what you're looking for is the compressed size on disk.

2 replies

josephlavine
Community Expert
josephlavineCommunity Expert
Community Expert
May 13, 2018

I ran a quick test using Export > Save for Web (Legacy) and using the settings for the attached image shows that I should have a JPEG that is roughly 1.8M (1.8MB), and when I check the closed file size on my desktop it matches.  However, as D Fosse mentioned, when the file is opened it is uncompressed and will be larger.

    O
    oliverm81709700Author
    Participant
    May 13, 2018

    Awesome!  Thanks for the explanation.

    D Fosse
    Community Expert
    D FosseCommunity ExpertCorrect answer
    Community Expert
    May 13, 2018

    That sounds like normal jpeg data compression. When you open a jpeg it is decompressed and essentially stops being a jpeg - when open it's just a pixel array like any other.

    It only becomes a jpeg the moment you save it to disk, and then the jpeg format uses very aggressive data compression to reduce storage file size.

    If you need a certain target file size for web, what you're looking for is the compressed size on disk.

      rejittiachan
      rejittiachan
      Participating Frequently
      May 13, 2018

      You can use File > Export > Save for Web (Legacy) option. (Shortcut Shift+Alt+Cmd+S). Down left, you can see the size of the to be exported file.

      Hope this helps.

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