Q2 file size after exporting from LR

[Dion]

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The Q2 DNG file is around 80++ MB but exporting as JPEG after processing in LR, I noticed that the JPEG file size becomes relatively small. For experimental purpose, I intentionally set the LR export criteria as follow :-

1) JPEG image quality to 100

2) Resize to fit as 100 Megapixels + 300 ppi

The JPEG export file size never exceeds more than 25 MB. It is around 18 MB to 23 MB.

Exporting as DNG file with either 1) embed fast load data or 2) embed original RAW file resulted in file size of about 38 MB only.

Is the JPEG and DNG exporting file size normal ?

Thank you

 

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[marchyman]

Lightroom uses lossless compression when exporting (or saving metadata to) DNG files.  The Q and Q2 do not use lossless compression, probably to enhance burst speed.  I'd expect exported DNG files from Lightroom to be significantly smaller that what comes out of the camera.  My Q images get reduced from about 44 MBytes to about 23 MBytes.  I'd expect Q2 images to be reduced in size by a similar factor.

[Dion]

Thanks marchyman

My concern is really on the small JPEG size notwithstanding I have set the criteria when exporting.

[sturkel]

So I just checked and depending on the % of the crop used my JPEG are 10-20 Mb per image. This is with Q2 raw files post-processed.  

 

[marchyman]

Jpegs are compressed a lot more than DNG for several reasons.   For one thing less data is being compressed as jpegs are limited to 8 bits/channel.  Jpeg compression is also lossy.  That allows use of more aggressive compression strategies.   Finally there is the compression quality setting.

Using a full size test image from my Q (6000 x 4000 pixels)

44.3 MB -- Original Q DNG

26.6 MB -- Compressed Q DNG

10.2 MB -- JPEG at quality 100

03.7 MB -- JPEG at quality 80

The difference between jpeg quality 80 and jpeg quality 100 are barely noticeable on my computer.  I usually use jpeg quality 85 for images destined for the WEB.   The extra data available in the DNG is necessary (IMHO) for editing.  I don't want to start my edit by throwing away data that the camera captures but does not exist in a jpeg.

Edited May 25, 2019 by marchyman