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kristinb55609253
Participant
June 19, 2018
Question

Jpg image sizing

  • June 19, 2018
  • 3 replies
  • 624 views

I'm suddenly having issues with my image sizing in Photoshop CC.  I am importing dng files that have been altered in Lightroom; the dng files are 20+ MB in size.  I am doing minimal editing in Photoshop, then saving the final images jpgs to upload to online galleries.  Most of my images were compressing down to 10-14 MB previously, but suddenly everything is in the 4-7 MB range.  I'm not aware of changing any of my settings, so I'm stumped as to why I'm getting smaller file sizes all of a sudden.  Any ideas?

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    3 replies

    Benjamin Root
    Benjamin Root
    Legend
    June 19, 2018

    Photoshop‘s default Save As JPEG compression is 8, your original numbers of 10-14 MB sound like 12. Shot in the dark, but I’d hazard a guess that Photoshop somehow defaulted back to 8.

    Personally, I used 10. A good balance between size and quality, IMO

    D
    Dynamic Office
    Legend
    June 19, 2018

    I wouldn’t worry too much about the file size when converting from .dng to Jpeg, as you’re probably already aware, jpeg’s use an algorithm and compresses the image - this happens every time you save a jpeg, so if you save a jpeg, then save that jpeg again it will compress it even more but a file size doesn’t mean the image quality is any less, it’s just the algorithm doing what it thinks is best.

    At any rate, if it’s for website viewing you tend to want the file size to be as low as possible for faster loading times.

    Take a look at Amazons home page, the images look high quality but are usually between 30kb-100kb

    To answer your question though, I must be honest I don’t know why it’s spitting out two different sizes unless you’re saving the jpeg, then re-saving the jpeg.

    K
    kristinb55609253Author
    Participant
    June 19, 2018

    I am aware that the file size number isn't crucial; it just seems weird that it is all of a sudden consistently giving me a much smaller file size than what I had been getting previously.  The images are being uploaded to a gallery where the client can then download the files for their use, so I want to make sure they are getting the best quality files. 

    Per Berntsen
    Community Expert
    Per BerntsenCommunity Expert
    Community Expert
    June 19, 2018

    Image content has a significant effect on the file size of a jpg - large flat or smooth areas compress well (small file size), whereas sharp detail (and noise) is harder to compress, and will lead to a larger file size.

    So my guess is that these images have less sharp detail and/or larger flat areas than your previous images.

    Consider the two images below, both exported at 80 quality from Lightroom. The bottom image has a file size 3.5 times larger than the top one, and the difference is entirely due to image content.

    41 kb

    146 kb

      D
      Community Expert
      DaveJCummingsCommunity Expert
      Community Expert
      June 19, 2018

      hmmm....when you're initially saving them in PS,  are you making sure they're saved as Maximum? Also, have you done any work to the images after you opened them in Photoshop?

      K
      kristinb55609253Author
      Participant
      June 19, 2018

      I am saving them to maximum size, yes.  Minimal editing in Photoshop; most is being done in Lightroom.

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