# Change JPEG preview size in DNG?



## MikeCaine (Mar 24, 2008)

I have previously converted some RAW files to DNG and I used the medium size JPEG preview. Now that I have a 3'" monitor these medium size previews look a little lost amongst the full size RAW files so I'd like to be able to change the JPEG preview of the DNG files to full size. Is there an easy way to do this?

Mike


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## Andrew Hayton (Mar 26, 2008)

Hi Mike,

I am not at my LR machine right now so am not sure if you can change the setting easily. Will have a look tonight when I get home. In the meantime you could have a look in the preferences and see if there is a setting and convert the files to DNG again. I would think that it would embed a bigger preview.
There may be a better way and someone else on here might know.


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## MikeCaine (Mar 26, 2008)

I had though about trashing my DNGs and recreating them from the RAW files but I had applied a few adjustments to the DNG that I'd like not to lose if possible. I'm not in front of Lightroom now either but I couldn't spot an update DNG option when working with DNG files, although I have been known to miss obvious things before


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## rcannonp (Mar 26, 2008)

Just curious, where is it that you see the difference in preview size?


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## MikeCaine (Mar 26, 2008)

If I double click on the thumbnail images the RAW files seem to fill me screen or more (25'' x 16'' pixels approx) whereas the DNG files just show a smallish preview in the middle of the screen. It wasn't very noticeable on my 2'" iMac, but the difference shows up considerably on my new 3'" monitor


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## rcannonp (Mar 26, 2008)

What application are you using to view the images? Preview? If you are only seeing the embedded preview then I would check to make sure that you have all of the latest camera raw udates from Adobe and Apple.


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## MikeCaine (Mar 26, 2008)

Lightroom. If I'm looking through a set of images then the RAW files fill the available space in the main middle panel but the DNGs with medium size preview barely use half of that space and look a little lost in comparison


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## rcannonp (Mar 26, 2008)

Doesn't LR create it's own previews? When I view CR2, med preview DNG, and large preview DNG files, they all look the same(on a 192'x12'' monitor).


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## Replytoken (Mar 26, 2008)

I believe that on the File Handling tab in the File/Catalog Settings menu you can change the settings for previews.  Since you can control when previews are discarded, you might be able to set things up so new previews are created at the size and quality that you desire.  You may also be able to flush the previews from LR, but I could be wrong there.  I am not certain how this woudl impact the DNG files if you do not have LR writing to the XMP portion of the file.  Perhaps a guru can provide additional information for our enlightenment?

--Ken


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## MikeCaine (Mar 26, 2008)

rcannonp said:


> Doesn't LR create it's own previews? When I view CR2, med preview DNG, and large preview DNG files, they all look the same(on a 192'x12'' monitor).



I'm going to have to have another look at exactly what I'm seeing when I get home. What I think I'm seeing is the RAW files occupying the whole of the main Lightroom panel, and DNG files only occupying about half that size. It dawned on me that I was using medium size embedded JPEG previews in the DNG converter so I'd assumed that was my problem and I needed to somehow upgrade the preview to the maximum size.


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## Victoria Bampton (Mar 26, 2008)

I haven't spent much time on DNG's, but looking at the file size, changing the preview size in preferences and then using Metadata menu > Update DNG Preview & Metadata appears to update the embedded DNG preview.

That said, the guys are right, the embedded DNG previews should have nothing to do with what you see in Lightroom as it generates its own previews.  Have you got the zoom set to a smaller size (top left, navigator panel)?


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## MikeCaine (Mar 27, 2008)

I had to go out last night so didn't have a chance to check. Will hopefully have a good look at it tonight

Mike


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## MikeCaine (Apr 2, 2008)

Sorry I didn't get back to this earlier, things are a bit hectic at the moment.

Anyway, I must be bonkers and it will teach me not to post from work about things at home as it turns out the smaller DNG preview issue wasn't with Lightroom, it was with iView

I use both Lightroom and iView in parallel as iView is better for DAM and I can just select a bunch of photos and then open and process them in Lightroom. 

I solved the problem by changing the LR preferences for a full size preview in DNG, then updated the DNG and then when I looked at them in iVeiw again I was getting the big preview rather than the medium preview

Sorry for the wild goose chase 

Mike


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## Brad Snyder (Apr 2, 2008)

Mike, not to worry, somebody, somewhere, sometime will learn something from this exercise.


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