• Adobe Photoshop

  information on image size is different depending on method used

  Posted by Jason Zaloga on April 4, 2014 at 7:26 pm

  The image size starting out is 72dpi resolution @ 1280x800px dimension.
  The final target output settings when using “Save For Web” in Photoshop should be:

  72dpi resolution @ 1280x800px dimension
  JPEG Quality:75 @ 246.7 Kilobytes.

  1. If I re-import the image that is supposed to be at 246.7 Kilobytes in Photoshop and click image size,
  it is telling me that the image is 2.93 Megabytes.

  2. When using Apple’s “Preview” app and click the inspector it is telling me that the image is 253 KB (Kilobytes).

  3. When using Apple’s “Quick look” feature, selecting the image then hit space bar, it is telling me that the image is 247 KB
  (rounded off) which is closer to the original final target output settings of 246.7 Kilobytes.

  4. Lastly, when I click Command i to get the image info, it is telling me it is 253 bytes or (254 KB on disk).

  Why is all the image info that is available so different and which method should I trust or use?

  Jason Zaloga replied 11 years, 11 months ago 2 Members · 2 Replies
• 2 Replies

• 

  Jonathan Ziegler

  April 5, 2014 at 6:18 pm

  Ok, you are seeing differences between files size and the “uncompressed” size in RAM. 246.7kB should be the compressed file size ON DISK, BUT 2.93MB is the memory size. Calculated by:

  800px x 1280 px x 3 channels (RGB) / 1024 / 1024 = 2.93MB

  JPEG compression will significantly reduce this at 75% quality by simply tossing out the stuff it doesn’t need or want.

  Hope this helps. 🙂

  Save early. Save often.

  Jonathan Ziegler

  http://www.electrictiger.com
  520-360-8293
• 

  Jason Zaloga

  April 6, 2014 at 4:57 am

  thanks

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