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DPChallenge Forums >> Photography Discussion >> Export from Lightroom Classic to 1200 pixels
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06/27/2019 08:10:07 AM · #1
I started recently to have a weird problem while exporting from Lightroom Classic - the maximum size of the exported JPEG files at 100% quality became very small. My settings:

Format: JPEG
Color Space: sRGB
Quality: 100
Limit File Size: unchecked i.e. max size

Resize to Long Edge: 1200
Resolution: 240

Sharpen for Screen: Standard


From a cropped photo of 5402x3039 I get the maximum file size of 563 KB for 1200 pixels long image, why so small? I used to have to restrict to 700KB but I don't need to any more. I think I have somehow lost the quality of the output but I don't know why. Searching Web did not produce anything. Any ideas?
06/27/2019 08:32:51 AM · #2
JPEG file sizes are highly dependent on the image characteristics -- the more detail, colors, or noise present the larger the file will be at any given compression setting.

Try taking the same image and way over-sharpening it (or add noise) and save with the same settings -- it will probably be larger.
06/27/2019 08:43:46 AM · #3
Originally posted by GeneralE:

JPEG file sizes are highly dependent on the image characteristics -- the more detail, colors, or noise present the larger the file will be at any given compression setting.

Try taking the same image and way over-sharpening it (or add noise) and save with the same settings -- it will probably be larger.

Yes, thanks, but the image has a lot detail and is in color. Similar images in the past were well over 700KB at 100% quality. I think there may have been a change of JPEG compression algorithms. I read that Export JPEG compression for Lightroom CC is different and more aggressive for use on mobile devices. I hope that didn't find its way to the desktop version :(
06/27/2019 08:49:04 AM · #4
If you are using Windows you might try saving as a TIFF out of LR and then use another program (like IrfanView) to save as JPEG and see if you get a better/different result.

Or, if the image looks fine after uploading, don't worry about the file size ... :-)
06/27/2019 09:34:39 AM · #5
JPEG compression is per the standard, and that hasn't changed in eons. So if file size seems smaller than it used to be for similar images, we need to look elsewhere for causes. As Paul pointed out, sharpening can have a (sometimes dramatic) effect on file size. I am wondering if the Lr sharpening algorithms have been tweaked to be less aggressive. Specifically, if they implemented algorithms that avoid sharpening areas without detail, it could dramatically reduce file size since you would not be "sharpening noise". Another possibility is the tweaking of resampling algorithms. If they improved those algorithms, it may well result in smoother tones and thus reduced file size in the resampled image. Finally, even in the absence of any changes to compression or resampling algorithms, the files from modern cameras are just better in this regard, so we *should* expect to see smaller files from like images.
06/27/2019 10:44:07 AM · #6
Thanks, Fritz and Paul. I noticed the change since the last update that introduced Texture slider, maybe the Export software was changed to accommodate this new feature. It would align well with Fritz's idea about changes to sharpening algorithms.
06/27/2019 12:09:32 PM · #7
I just tried the same file and everything else, I only changed the Limit File Size. At Limit 731KB, the Export produced file size of 730.51KB. I then changed the Limit to 730KB and got the Export JPEG of 499KB!

I think the change of any algorithms must have been dramatic. Hopefully this is just a bug and will be fixed in the next release.

PS I checked these JPEGS at 3:1 scale and I cannot tell the difference, I noticed though that the edges on both are very jagged at 3:1, not obvious at 1:1.

Message edited by author 2019-06-27 12:18:06.
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