Lightroom calculates image size incorrect

  • 1
  • Problem
  • Updated 2 years ago
I detected the problem, that each time steals my time.
If to cut the original image and then export it in e.g. 4.1 megapixels - an exported size will not have 4.1 megapixels.

Steps to reproduce.

1) Upload the image of e.g. 12 megapixels in e.g. CR2 format (3000x4000).
2) Cut the image from 2 sides (for example make it 2000x3000).
3) Now export this image: Command+Shift+E => Image Sizing => Resize to Fit - Megapixels => set 4 => press "Export" button.

Expected result:  exported image has 4 megapixels
Actual result: exported image has less than 4 megapixels
Photo of Andriy Slobodian

Andriy Slobodian

  • 1 Post
  • 0 Reply Likes
  • confused

Posted 2 years ago

  • 1
Photo of JaapV

JaapV

  • 30 Posts
  • 2 Reply Likes
If it has to fit within a frame of 4 mp, then inevitably the result must be less than 4 mp.
Photo of JaapV

JaapV

  • 30 Posts
  • 2 Reply Likes
Andriy, I forgot to mention that i did not follow your steps. I saw no reason to do so, because it seems to me that you misunderstand the word "fit": it does not mean "to be equal to" but "to be slightly less than".
The function is commonly used for photos that must be shown on a website that imposes a pixel limit: one pixel less than the limit is always safer than the exact limit.
Semantics...
Photo of Steve Sprengel

Steve Sprengel, Champion

  • 2613 Posts
  • 333 Reply Likes

This seems to be working for me, in the way it's designed to work where "mega" really means "million" not x1024x1024.

For example, I start with an arbitrary-cropped image:  1965x1344, tell LR to export as 4MP, and I get an image of 2418x1654 = 3,999,372 pixels which is just under 4,000,000 pixels and increasing the resize to one pixel larger in the larger dimension, 2419x1654 = 4,001,026, is larger than 4-million.

4 megapixels is actually 4x1024x1024 = 4,194,304 pixels or 4.194304 million, but the best you can do entering into LR is 4.1 or 4.2, so entering 4.1 is as close as you can get to 4-megapixels without going over.

If your issue is LR using million instead of mega then ok, but that's how it's designed to work and it isn't a bug.  It's the same with hard-drive where the raw bytes available is always million or billion or trillion not mega or giga or tera.

If you feel there is something else happening besides the difference in mega vs million then please give specific dimensions of both before and after export, instead of just saying it doesn't work. 


Photo of JaapV

JaapV

  • 30 Posts
  • 2 Reply Likes
Moreover, mega/giga/tera is very much subject to interpretation, as - for instance - hard disk manufacturers would have us believe :)