I'm downsizing a large batch of images that all need to end up as 1.5 to 2 MB jpegs. All of the images from my camera start at the same MB size in the RAW files, When I export/resize them they come out in varied sizes, in this case from 1.4 MB to 3.8 MB. I seem to have come across something that seems very simple that is kicking my butt. Are any of you aware of a way to control the image file size instead of pixel dimension when downsizing?
In the Export Dialog under <File resizing> select <Megapixels>.
The formula that worked for me is MegaPixels x 3 = File Size.
This formula is not mathematically exact but gives a good approximation for uncompressed 8-bit files Tiffs.
With JPGs it's a bit difficult to get to a certain file size because the compression comes into play, and even if you don't change the compression between images, the file size will be different for different images.
Try it with quality set to 100%. This would reduce compression to zero (?) and you would get (presumably) more consistent file sizes between different images.
Thanks for the help web-weaver. I gave that a try and it worked pretty well but when I limit the bigger output files to 2 MB the smaller output files come out at 1.1 MB. I need to find a way to have all of the files come out at 1.5 to 2. MB
I need to find a way to have all of the files come out at 1.5 to 2. MB
This can only be done by adjusting the quality slider in the Export dialog box, and/or the export size, one photo at a time. There is no automated way in Lightroom.
Furthermore, I consider this to be a rather inappropriate requirement because the JPG size tells you nothing about the image quality. There is no logical reason to have this restriction, as far as I know. (If the restriction was "all files under 2MB", I can understand that in certain situations, but I cannot understand why you would insist a photo must be between 1.5MB and 2MB)
Try it with quality set to 100%. This would reduce compression to zero (?)
Even at a quality level of 100 (not 100%), there is some compression.
Thanks dj, I fell the same way about the restriction. What I'm doing now is to export as described before and limiting the maximum MB to 2, then taking everything that falls below 1.5 and reprocessing that group separately. It worked with a group of 55 photos and only one image fell below 1.5 in the second batch. I guess that's what I'm stuck with, but I still can't figure out why the smaller file exports are determined by the larger files. That doesn't make sense.
... but I still can't figure out why the smaller file exports are determined by the larger files. That doesn't make sense.
I don't really understand what you are saying here ... however ... the thing that doesn't make sense is trying to relate JPG file sizes to anything else that might be descriptive of the photo. This simply cannot be done because there is no relationship that can be discovered between JPG file size and number of pixels and quality level. You are wasting your time trying to figure it out.
And if it was me, I would push back against whoever provided you with this restriction for unnecessarily making your life difficult.
I'm downsizing a large batch of images that all need to end up as 1.5 to 2 MB jpegs.
Ditto for me. Could you please explain exactly why the file size needs to be within the 1.5 MB to 2.0 MB range, and how the Exported files are to be used (stock photo house, web page, or other).
All of the images from my camera start at the same MB size in the RAW files,
This is the "open" image file size (i.e. pixel bit map), which web-weaver explained is the Camera Megapixels x3 (RGB pixels).
What file format do you need to Export from LR and what opened image file size is required?
What I mean is that if you export the files individually that come out smallest when exported in a batch they export to a proper size, but when exported as part of a batch they export to a much smaller size.
Please provide the LR version (i.e. 3.6, 4.1,??) you are using and ALL of the Export settings used for both the single and multiple file (i.e. "batch) Export. Did you use the exact same settings for both, and did you do anything differently for the sinlge file versus multiple file export? There should be absolutely no difference between the two, unless you changed some settings, or inadvertently used different files. For example, if you shoot raw + JPEG you may have accidently used the JPEG instead of raw for one of the Exports. This may give you slightly different Export file sizes.
trshaner, I have no idea why the files have to be that size, that's just the requirements of the customer. I'm trying to convert from RAW to jpeg.
You need to talk to your customer about this requirement. As dj_page and I have already told you this makes no sense! I think your customer is confusing "open file size" (i.e. camera megapixels) with "actual file size." Using a Canon 5D MKII raw image:
Camera Megapixels (Mp) = 5,616 x 3,744 = 21.03 Megapixels = 21.03 (Mp) x 3 (RGB) x x 2 (16 bit data) = 120 MB (126,189,568 bytes)
1 Megabyte= 1,048,576 bytes
LR Export File Size
TIFF, ProPhoto RGB, No Compression, 16 bit depth = 120.0 MB
TIFF, ProPhoto RGB, ZIP Compression, 16 bit depth = 101.9 MB (lossless compression)
JPEG, sRGB, 100 Quality = 13.9 MB (JPEGs are 8 bit depth lossy compression)
JPEG, sRGB, 90 Quality = 7.6 MB (JPEGs are 8 bit depth lossy compression)
JPEG, sRGB, 80 Quality = 4.8 MB (JPEGs are 8 bit depth lossy compression)
ALL of the above image files contain the exact same number of Camera Megapixels (i.e. have the same resolution)!
Message was edited by: trshaner Corrected TIFF no compression file size.