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Author Topic: LR Web Gallery Creation and DNG.  (Read 5211 times)

Nick Rains

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LR Web Gallery Creation and DNG.
« on: February 23, 2008, 11:59:39 pm »

Given that Adobe created DNG I find it strange that Lightroom has to process every DNG file as though it were a RAW file in order to make a web gallery. Surely the embedded previews are entirely adequate to use as source data since they are a. colour accurate and b. only intended for web use anyway.

When LR creates DNG files from CR2 files it has to process the files, fine, this much is obvious. It takes a certain amount of time to do this - about 10 secs per image on my PC. Why then does LR re-process the same images, taking about 17 secs per image rather than use the already generated Jpeg previews?

An example:

LR1.3  - 117 Canon 5D DNG files to Flash gallery - about 33 mins.

Photo Mechanic - Same files, also Flash gallery -  2 mins.

LR is re-processing files that have already been processed, PM is just using the previews.

Is there a good reason for LR to process files twice like this?
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Nick Rains
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The View

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LR Web Gallery Creation and DNG.
« Reply #1 on: February 24, 2008, 12:57:48 am »

DNG is a RAW format. There isn't just one RAW format, there are several. Every camera maker has one, and Adobe's DNG creates a RAW format that wouldn't disappear with a generation of camera models.

Not sure about your process creating a web gallery.

But here's a step by step guide on how it works flawlessly. There is not difference if the selected files are DNG or any proprietary RAW format, TIFF, PSD, etc.

1. Create a collection, name it e.g. "landscape gallery"

2. Drag all the images into the collection. The originals stay in their original location, but virtual copies will show up in the collection.

3. Once you have all the images in your collection, click the web module.

4. In the web module you decide which mode to use to display the photos. I, for example, use the airtight viewer, and so I click on the airtight viewer.

This shows all the selected images in the airtight viewer. There are controls to the right, where you can adjust image size and quality. Lightroom automatically creates JPEGs out of the images in the selection.

Some of my files, coming from Photoshop, are quite large, but the conversion is quick.

Key is, that you don't have to reformat any photo. Changing to the web module does this automatically, and quickly. No way it takes a minute per photo.

Hope this helps.
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Nick Rains

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« Reply #2 on: February 24, 2008, 01:12:26 am »

Quote
No way it takes a minute per photo.
[a href=\"index.php?act=findpost&pid=177011\"][{POST_SNAPBACK}][/a]

Thanks for the detailed post. I agree with your methods and do pretty much the same myself with the exception of not using Collections.

It takes 17secs per photo on my PC. In other words LR is doing a full RAW conversion from the DNG file to the smaller sized jpeg.

My point is that this conversion has already been done when converting my CR2 RAWs to DNG. I'm puzzled that LR feels the need to go to all this effort re-converting the files when the images it needs are already embedded in the DNG file. This double handling takes so much longer, as per my examples.

How long do your RAW files take to generate a web gallery?
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Nick Rains
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john beardsworth

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« Reply #3 on: February 24, 2008, 07:47:17 am »

Nick

The short answer to your original question is No, there's no good reason. I'd love Adobe to have a draft mode for Web where they use the embedded preview or any adjusted preview, and I'd use it all the time. I still generate galleries of DNGs from iView because of the speed advantage.

If you want to use LR, that advice about Collections was good. As well as letting you control which images were in a gallery, a Collection silently remembers the last Web settings which were used on it.

John
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digitaldog

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« Reply #4 on: February 24, 2008, 10:54:18 am »

Quote
Given that Adobe created DNG I find it strange that Lightroom has to process every DNG file as though it were a RAW file in order to make a web gallery. Surely the embedded previews are entirely adequate to use as source data since they are a. colour accurate and b. only intended for web use anyway.

I'd like Schewe to comment but I don't know what you say is necessarily true. First, how large are you building the previews in DNGs (you have control over this) and how large are the images in the web gallery? I think its quite possible that the embedded previews are used IF they are updated (remember too, you need to update them at some point if you alter a rendering slider in say Develop).

Would you want DNG's to update the preview after every single edit move? That would not be effective. At some point, LR has to update the previews for use. There's also the preview cache (what you see when you move the sliders) and that size compared to what you wish to use the newly rendered preview for (is it large enough?).
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Nick Rains

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« Reply #5 on: February 24, 2008, 04:25:18 pm »

Quote
I'd like Schewe to comment but I don't know what you say is necessarily true. First, how large are you building the previews in DNGs (you have control over this) and how large are the images in the web gallery? I think its quite possible that the embedded previews are used IF they are updated (remember too, you need to update them at some point if you alter a rendering slider in say Develop).

Would you want DNG's to update the preview after every single edit move? That would not be effective. At some point, LR has to update the previews for use. There's also the preview cache (what you see when you move the sliders) and that size compared to what you wish to use the newly rendered preview for (is it large enough?).
[a href=\"index.php?act=findpost&pid=177073\"][{POST_SNAPBACK}][/a]

Thanks John and Andrew

Assuming fully LR-previewed DNGs and large embedded jpeg previews LR still appears to fully render the RAW data to generate the web gallery images. Given that the embedded jpegs are full 5D size and the previews are the vanilla 1440px wide ones, then there is plenty of image data to derive the 500px wide web images from. Even the LR previews would be fine.

I just did a little test...

4 DNG images in LR catalog, nothing else, fully previewed etc.

Export 4 full res 8 bit TIFFs : 35s
Export same to web gallery : 55s plus 2s for gallery gen.

No doubt the extra time is taken sorting out the web gallery structure but it seems clear from the progress that the RAW data is being rendered.

As far as I can tell LR re-renders the DNGs to create web galleries - there seems no good reason for this. Adobe put the full res embedded previews in DNG for a reason, and it's a great idea. Other apps seem to have no trouble utilising this feature so it's ironic that LR can't or won't.

I find LR so frustrating, on one hand it is (almost) really useful and well thought out, and on the other hand it is rubbish at simple tasks like quick browsing and 100% views to check sharpness.
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Nick Rains
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The View

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« Reply #6 on: February 27, 2008, 06:23:01 pm »

Quote
Thanks John and Andrew

Assuming fully LR-previewed DNGs and large embedded jpeg previews LR still appears to fully render the RAW data to generate the web gallery images. Given that the embedded jpegs are full 5D size and the previews are the vanilla 1440px wide ones, then there is plenty of image data to derive the 500px wide web images from. Even the LR previews would be fine.

I just did a little test...

4 DNG images in LR catalog, nothing else, fully previewed etc.

Export 4 full res 8 bit TIFFs : 35s
Export same to web gallery : 55s plus 2s for gallery gen.

No doubt the extra time is taken sorting out the web gallery structure but it seems clear from the progress that the RAW data is being rendered.

As far as I can tell LR re-renders the DNGs to create web galleries - there seems no good reason for this. Adobe put the full res embedded previews in DNG for a reason, and it's a great idea. Other apps seem to have no trouble utilising this feature so it's ironic that LR can't or won't.

I find LR so frustrating, on one hand it is (almost) really useful and well thought out, and on the other hand it is rubbish at simple tasks like quick browsing and 100% views to check sharpness.
[a href=\"index.php?act=findpost&pid=177117\"][{POST_SNAPBACK}][/a]

Nick, how old is your computer?

The processing times and problems you are reporting sound like an at least 5 year old machine.

Or: how much RAM do you have? Sounds like you have 512mb or so. For LR, or any modern image app, you should consider having at least 2 or 3 Gb RAM.

Dual processors help.

Or you have serious system trouble. Maybe it helps to set up your system again.

Or, if you have a PC, you could have a virus, or the aftermath of a virus. Or your virus software checks all your photo files when processing, which could cause delays.

Another idea: did you do the upgrades to 1.3? There was an upgrade, which was sluggish, I think it was 1.1.

1.3 should be quick and without problems.

I'm on a Mac, a 24" iMac, dual processors, 3 GB Ram. LR is quick, and no problems.
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Nick Rains

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« Reply #7 on: February 27, 2008, 07:36:41 pm »

Quote
Nick, how old is your computer?

The processing times and problems you are reporting sound like an at least 5 year old machine.

Or: how much RAM do you have? Sounds like you have 512mb or so. For LR, or any modern image app, you should consider having at least 2 or 3 Gb RAM.

Dual processors help.

Or you have serious system trouble. Maybe it helps to set up your system again.

Or, if you have a PC, you could have a virus, or the aftermath of a virus. Or your virus software checks all your photo files when processing, which could cause delays.

Another idea: did you do the upgrades to 1.3? There was an upgrade, which was sluggish, I think it was 1.1.

1.3 should be quick and without problems.

I'm on a Mac, a 24" iMac, dual processors, 3 GB Ram. LR is quick, and no problems.
[a href=\"index.php?act=findpost&pid=177827\"][{POST_SNAPBACK}][/a]

It's not the machine, it's merely the way LR works re-processing the DNGs when it doesnt have to.

P4 3.2Ghz. 2Gb RAM 18 months old LR1.3 no other issues with speed. LR is OK in other areas, not exactly nimble but not too bad.

Cheers

Nick
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Nick Rains
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NikoJorj

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« Reply #8 on: February 28, 2008, 09:43:30 am »

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My point is that this conversion has already been done when converting my CR2 RAWs to DNG.
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Sir no Sir, it hasn't!
As said, the CR2 to DNG step is not demosaicing, it's only about translating from one RAW format to another (that should be more widely readable).

And for any export, I understand LR always does the demosaicing from the RAW files - it should give better quality than previews (it might be interessant to have someone authorized answering this bit, Jeff Schewe maybe?).

But I also agree it could be nice to have a "draft export" option when in a hurry, similarly to the "draft print" option (which does indeed take the available previews, [a href=\"http://learn.adobe.com/wiki/display/LR/Print+in+draft+mode+-+Basics]or sends thumbnails if there ain't any[/url]).
It might be appropriate to ask for for this feature on the dedicated Adobe forum.
« Last Edit: February 28, 2008, 09:44:41 am by NikoJorj »
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Nicolas from Grenoble
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Nick Rains

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« Reply #9 on: February 28, 2008, 05:04:25 pm »

Quote
Sir no Sir, it hasn't!
As said, the CR2 to DNG step is not demosaicing, it's only about translating from one RAW format to another (that should be more widely readable).

And for any export, I understand LR always does the demosaicing from the RAW files - it should give better quality than previews (it might be interessant to have someone authorized answering this bit, Jeff Schewe maybe?).

But I also agree it could be nice to have a "draft export" option when in a hurry, similarly to the "draft print" option (which does indeed take the available previews, or sends thumbnails if there ain't any).
It might be appropriate to ask for for this feature on the dedicated Adobe forum.
[a href=\"index.php?act=findpost&pid=177959\"][{POST_SNAPBACK}][/a]

You are partly right - CR2 to DNG does indeed demosaic the RAW data to generate the full size Jpeg preview.

It's this 'draft export' as you call it that would be so useful. Generating 600px wide images for a web gallery from the full RAW data is total overkill and a waste of time. Using camera previews is obviously less than ideal, but the whole point of DNG previews is that they are a: full sized and b: properly converted from the RAW data using ACR. They are thus absolutely ideal for generating web galleries.

This is why my gallery took 35 mins in LR and 2 mins in Photo Mechanic with identical quality results.
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Nick Rains
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