Lightroom: How to view uncompressed JPEG file size

  • 2
  • Question
  • Updated 6 years ago
  • (Edited)
When I save a raw file to jpeg, Lightroom 4 shows the file size which is the compressed size of the file. Is there any way of seeing the uncompressed file size. The reason is that my stock library requires jpeg files of a certain uncompressed size.

Regards
Photo of Arthur West

Arthur West

  • 17 Posts
  • 0 Reply Likes

Posted 6 years ago

  • 2
Photo of LRuserXY

LRuserXY

  • 426 Posts
  • 41 Reply Likes
I assume "uncompressed size" means count of 8-bit-pixels times count of RGB-channels (= 3), so your stock library effectively gives you a pixel count constraint.

Instead of "Limit file size to:", you can use "Resize to fit" with "Megapixels". E.g. if the requirement is "30 Megabyte", you can compute Megapixels from Megabyte by dividing by 3 (RGB channels), so you enter 10 Megapixels. Don't forget to uncheck "Don't enlarge" to allow upscaling.

P.S. Sometimes people say "Megabyte" (1.000.000 byte) but actually mean "Mebibyte" (1024 * 1024 = 1.048.576 byte). If this is the case, you have to increase the megapixel count slightly by that factor 1,05, e.g. 10,5 megapixels for the above example. Round up or down depending on whether 30 megabyte is a minimum or maximum constraint. BTW: "Megapixel" always means 1.000.000 pixels, as far as I know.

Edit/P.S. 2: I find it strange that a stock library has a megabyte requirement. Are you sure that they say megabyte and not already megapixel? If they want megapixel, you don't have to convert and can enter the number directly into the megapixel field of the export dialog.
Photo of Arthur West

Arthur West

  • 17 Posts
  • 0 Reply Likes
Thanks.

The quote from the stock library "What's important is the uncompressed (opened) file size. The opened file must be at least 24mb at 8bit to get through our quality control"

My problem is that I use Lightroom as a library and the only way I can find to see the uncompressed size, is in Photoshop. This means that I have to open the images in Photoshop, and was hoping to find a quicker way, ie see the uncompressed size in Lightroom. I only consider files for the stock library at a later stage, and not at the time I convert them to jpeg. I have only recently decided to use a stock library and need to select the images, making sure I meet the size requirements.
Photo of LRuserXY

LRuserXY

  • 426 Posts
  • 41 Reply Likes
Ok, so they really mean Megabyte. 24 MB is an equivalent of 8 Megapixel (which seems reasonable), or if they mean 24 MiB (MebiByte), the equivalent is 8.388608 Megapixel or rounded for LR 8.4 Megapixel.

So you can use "Resize to fit" with "Megapixels" and a value of 8,4 to scale up images so they fit the requirement. Note that you cannot instruct LR to export at a minimum MP setting (as far as I know), so images actually larger than 8,4 MP will be downscaled to 8,4 MP.

By the way: If you say "Lightroom 4 shows the file size which is the compressed size of the file", do you mean the number that you enter in the export dialog for "limit file size to"? I ask because I don't know any other place where LR shows the (predicted) file size.

The only way to know the uncompressed size *independent* of exporting is the information overlay configured to "pixel dimensions after crop" (or similar, I don't recall the exact name) and manually calculating X * Y * 3. Perhaps this is worth to post as an idea, to have two new options there: "uncompressed size after crop (8 Bit)" and "uncompressed size after crop (16 Bit)".
Photo of Arthur West

Arthur West

  • 17 Posts
  • 0 Reply Likes
Lightroom gives the size of the compressed file size and the type of file under the Exif and IPTC data on the right under the heading of Metadata.

In Photoshop 6, the uncompressed size it is shown at the bottom left hand corner - after selecting "file size" from the drop down.
Photo of LRuserXY

LRuserXY

  • 426 Posts
  • 41 Reply Likes
Ah, ok, now I understand. Sorry, I always thought about the export dialog until now...

I suspect that the uncompressed size is not shown because it a) depends on the crop and b) depends on whether the image is exported later as 8 bit or 16 bit - and raw itself does not have an "uncompressed size". So strictyl speaking it is not part of the metadata.

Perhaps the best solution really would be to add "uncompressed size after crop (8 Bit)" and "uncompressed size after crop (16 Bit)" for the information overlay.
Photo of Rob Cole

Rob Cole

  • 4831 Posts
  • 382 Reply Likes
DevMeta supports megapixel metadata (crop-width x crop-height), if that would help. To get bytes, you'd have to multiply by 3.
Photo of Arthur West

Arthur West

  • 17 Posts
  • 0 Reply Likes
Thanks for all your replies.