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Why bother with full size jpg preview in DNG?

T

tmai

Guest
Hi, first post with a question for people who have started using DNG in their LR workflow.

I use ImageIngester Pro to ingest the pictures from CF cards. Part of the ingestion is to generate DNG in new directory with full size jpg previews, lossless compression using Adobe DNG Converter app. Then I import the DNG into LR from their current location.

From personal observation and reading multiple threads in this forum, it's clear that LR has its own preview cache and doesn't read the preview embedded in the DNG file.

I understand that other 3rd party software take advantage of the DNG preview but why not LR? Why does LR even have the option to embed a full size preview (in the Convert to DNG dialog box) if it's not going to use it?

My main aim in moving to DNG format was to cut out the 'rendering larger preview' stage, hoping that reading the DNG preview would be faster than rendering a new one.

The other goal was to slow down the growth of the LR preview cache file. Even after discarding ALL 1:1 previews from the catalog, my cache file was still over 25GB. I had to delete it and let LR create a new one.

I'm starting to think that DNG (even with its other benefits) does not meet my needs while using LR.

BTW, I'll admit that on my computer, the rendering of larger preview takes all of 2 seconds. Not much but when working with 5''+ shots after a photo shoot, it adds up.

My running Mac Leopard 1'.5.2 with:

Intel Dual Core 2.7Ghz
4GB RAM
75GB Raptor HDD (it holds LR catalog and preview cache)
75'GB HDD with 3Gbps SATA interface (holds the RAW/DNG files)
 
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Oct 8, 2007
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"I understand that other 3rd party software take advantage of the DNG preview but why not LR? Why does LR even have the option to embed a full size preview (in the Convert to DNG dialog box) if it's not going to use it?"

Essentially the main reason has been as you describe, and it would be great to see LR using it too - some of us have been asking for it since day 1. Since its Mac-limited competitor now has a preview mode which uses these embedded previews, there's renewed hope that Adobe's team will see the sense of what we've been saying.

John
 
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