Jpegs From Lightroom

Two weeks ago, in the post Lightroom 3.2 RC I wrote “they haven’t tackled any of those things I find most annoying – like ‘Export’ giving lousy soft and over-large file size small jpegs.”

I met bahi a couple of months back at one of the monthly London meetings of Photo-Forum – well worth attending if you are in London on the 2nd Thursday of the month – it takes place in Jacobs Pro Lounge in the basement of their New Oxford St shop, from 6-8pm and afterwards we enjoy free food at a nearby pub paid for by a raffle during the meeting – the prizes are usually prints donated by the photographers who present work that evening.

Bahi is from Shoot Raw, an organisation that delivers support and training for photographers in digital photography, including Lightroom training and in a comment to that earlier piece  gives a useful link to Jeffrey Friedl’s analysis of file size vs quality for Lightroom JPEG export, and also asks me to go into more detail about the problem I mention.

When I read his comment I’d just been going through some of the pictures I took at Notting Hill yesterday and so decided to use the picture I’d just developed in Lightroom 3.2RC(on PC) as a fairly random example.

This is the full image – scaled down from the original D700 raw file taken at ISO 800 from 42656×2832 px to 600×399 px (and displayed here at 450x299px.)

© 2010, Peter Marshall

Not one of my greatest images!

First I tried using File Export to produce this file – here are the settings I used :

At 70% quality the file size for the 600-399px was 312kB.
At 30% quality the file size for the 600-399px was 254kB.

I tried to get File Export to produce a file using a file size limit of 150 and200Kb, but both times it reported it was unable to do so.

I selected the file and went to the web module in Lightroom, outputting a web site containing this file. I used the same 70% quality setting as before. The file produced was 118kB.

Here are some 300% details from the three Lightroom jpegs – as you can see, despite the huge file size differences the two 70% files are very similar.

© 2010, Peter Marshall
300% view of detail: File Export, Quality 30, 254 kB file

© 2010, Peter Marshall
300% view of detail: File Export, Quality 70, 312 kB file

© 2010, Peter Marshall
300% view of detail: Web Output, Quality 70, 118 kB file

[These files were created by viewing the files at 300% in ACDSee Pro, capturing with PrintScreen and pasting into Photoshop and cropping.]

70% is the setting I currently use for My London Diary, generally giving file sizes that are reasonable for broadband users – even on a page with a dozen pictures. Back in the old days of slow dial-up I used greater compression (and some special software that could actually use different compression levels on different areas of the same image) to trim file sizes to the bone, but this is no longer needed.  Before switching to Lightroom I had moved on to batch processing from full-size images with ACDSee Pro, which typically seemed to produce comparable quality with file sizes a little  smaller than Lightroom.  It isn’t possible to simply select an equivalent quality setting, but files slightly under 100kB from ACDSee seemed comparable to the Lightroom 70% file.

I’ve not investigated this Lightroom problem in great detail, butI get the impression it gives the largest files from those images I’ve worked on most with the tools such as the adjustment brush.

Friedl in his piece at the link given above points out that despite having quality settings labelled 0-100 actually only implements 13 quality levels  – just like Photoshop. I think you also get those same 13 quality levels if you use the checkbox to limit file size, but the file sizes can be different. Using quality 92 (or rather 85-92) on the above image gave a file size of 3748 kB, while limiting the file size to 5000 kB produced a visually identical file of 3550 kB.

Long, long ago when I produced jpegs using a DOS command line program I there were at least two parameters which had to be specified. One was a 1-100 setting for the quality of the match required between cells which would be replaced by the same cell, and the second was some kind of smoothing function. I don’t know that we need that kind of control, but perhaps we could be offered a little more than we have at present.

2 Responses to “Jpegs From Lightroom”

  1. bahi says:

    Hi, Peter.

    In your previous mention of these issues, you hinted that you might be experiencing this more often (or perhaps exclusively) when you export images in which you’ve applied a significant number of local adjustments. Is this still the case? I ask because in Lightroom, all of your brushwork and gradients are stored as metadata—every stroke.

    I just tried a comparison of the built-in metadata remover (the check-box that says “Minimize Embedded Metadata”) with a test installation of Mr Friedl’s Metadata Wragler and got the following results, beginning with a 10-megapixel Nikon raw image with a couple of exposure gradients and a little local brushwork, saved as a 70% JPEG at 600 pixels longest edge and with low screen sharpening applied. The first setting on each line below refers to the Lightroom checkbox, the second to the Friedl plug-in setting.

    All metadata preserved, no wrangle: 115KB.
    “Minimize embedded metadata”, no wrangle: 75KB
    “Minimize embedded metadata”, full wrangle: 49KB.
    All metadata preserved, full wrangle: 49KB.

    Mr Friedl’s wrangler comfortably out-wrangles the built-in Lightroom metadata remover. When I create a new collection in Lightroom containing just that same image and export using the web module (600 pixels, low sharpening, no watermark), I get a 53KB image. The large JPEG file size is beginning to look like a metadata issue. When you get a chance, could you test with a copy of Jeffrey’s Metadata Wrangler on your test image and post your results?

    Thanks for discovering and reporting on this. Not only had I never noticed it, no one had ever mentioned it to me either. (Obviously, there are downsides to removing all metadata… I know there’s no need to go into them here.)

    When we get to a confirmed result on this, I’ll put in a pointer to this article on my side as well. Thanks again.

  2. You are right.

    Using Lightroom’s minimise from the export module for the 70% file I get 151kB – still rather more than from the web module’s 118kB.

    With Friedl’s program and removing everything except ICC profile, EXIF copyright and create date and keeping all IPTC metadata it goes down to 108kB, or with a slightly fuller set of data which I’ve saved as a preset, 113kB.

    So I guess unless LR sorts out its act on this, there is a choice either of using Metadata Wrangler or exporting via the web module. The option that MW has to give the file modified date as the creation seems useful to me as well.

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