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Participating Frequently
October 4, 2019
Question

Photoshop resizing is giving wrong file size

  • October 4, 2019
  • 3 replies
  • 2381 views

I'm resizing some images for upload to a web page for an art competion. I open the image, adjust using levels, merge down to the background layer, resize using image size, check the file size is 4.83 mb. But when I go to upload, my Mac is telling me that the file size is 1.1mb, NOT 4.83 mb. I've never seen this before, what's going on??

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3 replies

Trevor.Dennis
Community Expert
Community Expert
October 4, 2019

Can you give us a link to the competition rules?  It is unlikely that they require an exact file size.  It's more likely to be a maximum file size, and maximum pixel size.  The file size will depend on how 'busy' the image is, because JPG compression will be more effective on a image with few colour transitions, than on a noisy complicated image.  The trick is to use the highest JPG quality setting you can get away with, while staying below the maximum file size.

 

Also make sure your image has the required colour setting which is usually sRGB.  If you submit an Adobe RGB image, for instance, then the colours are likely to be muted and dull when displayed to the judges.  I've tripped up with this one myself moaning about the projector calibration when it was actually my mistake. 

Participating Frequently
October 4, 2019

https://www.callforentry.org/uploading-images-audio-and-video-files/

  • File Type: JPEG or JPG only.
  • File Dimensions: 1,200 pixels or greater on the longest side.
  • File Size: Under 5 MB.

I've set compression to 12 (maximum), which does compress a file size of 7.92 mb down to 1.3 mb, but what's driving me nuts is trying to figure out what file size to start with to get best quality. I have set the color space to SRGB.

D Fosse
Community Expert
Community Expert
October 4, 2019

The piece in the puzzle you're missing is jpeg compression. File size on disk/over the wire depends on the data compression applied when saving.

 

Image size shows you the decompressed size of the data, as it sits in RAM. Layers are not counted.

Tom Winkelmann
Inspiring
October 4, 2019

You confuse file size with image size...

Participating Frequently
October 4, 2019
I thought they were the same, please explain?