DNG Conversion - preview size

In lightroom when converting files to DNG on the pop-up screen is the Choice: Size of the Preview file: Large, Medium or Do not create.
1. what is the file size for large and medium?
2. What is the impact of NOT creating a preview? When I've tested NOT creating a file I can still open the file in my lightroom grid and loupe view. I can also view it in Windows vista Preview when right clicking on the image file on my hard drive.
3. Where do these "Previews" come into play?
4. Also, I have noticed that if I convert a JPEG file to DNG the file size is about 4x larger. Should I reserve DNG for only my raw files such as my .mrw and .cr2? Has anyone else observed an increase in file size after DNG conversion?
5. What is the deal with DNG anyway? I havn't seen the big manufactures like Canon with the new EOS-1D Mark IV and Nikon's new D3s,include the DNG as a file format selection on their cameras. What do they know that I don't, about DNG?

1. what is the file size for large and medium?
Medium is screen sized, the other option is full sized, not large.
2. What is the impact of NOT creating a preview? When I've tested NOT creating a file I can still open the file in my lightroom grid and loupe view. I can also view it in Windows vista Preview when right clicking on the image file on my hard drive.
Lightroom generates it's own preview. It's just handy for portability, so how the file looks is available to programs that can't understand the internal settings.
3. Where do these "Previews" come into play?
Lightroom will use them in Library intially. Like I said above, it's handy for other programs for managing and printing with the Lightroom settings, especially with a full sized preview.
4. Also, I have noticed that if I convert a JPEG file to DNG the file size is about 4x larger. Should I reserve DNG for only my raw files such as my .mrw and .cr2? Has anyone else observed an increase in file size after DNG conversion?
You should. The JPEG doesn't get converted to a Raw, it's just convenient to have all DNG. The increase happens because Lightroom removes the JPG compression AFAIK.
5. What is the deal with DNG anyway? I havn't seen the big manufactures like Canon with the new EOS-1D Mark IV and Nikon's new D3s,include the DNG as a file format selection on their cameras. What do they know that I don't, about DNG?
Nikon and Canon have proprietary information in their Raw files. Yes it's rather a pain when they release a new camera. Sticking to a DNG format would really help with this, if they came on board. DNG is just a way of providing a common Raw format.

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DNG conversion fails sporadically with Get Photos From Camera

Camera: Canon 40D and 5D
XP SP2
CS3
Bridge 2.1.1.9
ACR 4.4.1
DNG Converter 4.3.1
Importing my files to Bridge using the Get Photos from Camera (GPFC) option results in sporadic DNG conversion failure. There's no pattern, just a lump of files that don't get converted at the end of the process. It's very frustrating because I have to manually go back and find the files that failed and use GPFC option again. Even then sometimes it fails again!
I'm attached to using the GPFC option instead of the standalone DNG converter because GPFC lets me automatically make a backup file to another disk and adds a template. But even when I use DNG Converter to import the files off my card, DNG fails for some of the files. Purging the cache only works half the time and for some of the files.
Is there any solution to the GPFC problem? I've seen people have similar problems, but with no real conclusions...
Any ideas? Thanks in advance.

Ramon,
No, I have tried purging/refreshing before and it doesn't help, because the un-converted CR2 files are just skipped over and put in the same destination folder as the successfully converted CR2 files (to DNG). I thought it might be a memory issue, but I never have any other applications open. As a test, I purposely opened some other applications to see if MORE CR2 files would be skipped, but the amount of files skipped was still random.
My "DNG Conversion Settings," accessed through the Get Photos From Camera dialogue, is set to:
Jpeg Preview: Medium Size
Compressed (Checked)
Preserve Raw Image (Checked)
Embed Original Raw File (UN CHECKED)
Could some of my Edit>Preferences>Cache options be overloading things and causing skips? I use the default settings because I wasn't confident with messing around with the cache.
Thanks

Embed Original Option for DNG Conversion

I have switched over my digital workflow now to DNG. I would love to see Adobe add an option to embed the original RAW file to it's DNG conversion in Lightroom. I was hoping that someone from Adobe would read this and take this suggestion into consideration...if not in v1.1, maybe in a future version. Thank You!

Ok, I am a novice here, but I am wondering:
What is the advantage to embed the original RAW into a DNG?
I believe I understand the value of the DNG: that it provides a single format for RAW data that simplifies the job software needs to do to render the RAW data, rather than needing to translate a zillion file formats. Also it removes the need for sidecar XMP files. OK, that sounds like good things.
So, assuming one already has a good backup of the RAW stowed away somewhere, and also assuming that the RAW-to-DNG converter is competant to do what it is supposed to, Why would one want the RAW embedded in the DNG?
One other question: would embedding the RAW file double the size of the DNG?
Thanks

Did my NEF to DNG conversion work properly?

I had read that when I convert to DNG in Lightroom (v4), the file sizes will drop by about 20% (I checked the check box for compression). I'm converting from a batch of 16-bit NEFs I created when scanning slides using the Nikon LS-5000 scanner. Those scans and files were created with Nikon Scan 4.0. After doing the conversion in Lightroom, the DNG file sizes are around 3MB-17MB. The original NEF files were about 135MB. Where in the world did all my data go? I'm concerned that the conversion to DNG threw away a ton of the original data. How is that much of a reduction possible? I'm hoping that there wasn't some catastrophic problem during the conversion, as I also checked the check box to delete the originals after the conversion is finished.
The image quality seems to be okay when looking at the DNG files in Lightroom.
Thanks,
Jay

I scanned at the full resolution (4000dpi, I think) of the LS-5000. The DNGs all appear to have their full original resolution, 5782x3946. This was one of the first things I thought about, too, but the resolution doesn't appear to have been changed any.
Jeff, upon re-opening the Convert Photo to DNG dialog box, I see that I did check "Use Lossy Compression." I spaced. I belived I was telling it to use lossless compression (I was assuming that no compression would have been used otherwise). So the conversion makes them into a high-quality JPEG, basically (but still 16-bit)? If I don't check that, will the DNG conversion use lossless compression, or no compression at all?
These slides are from a few decades to several decades old, all shot by my dad. I'm wondering if I would even see any degradation from using the lossy compression option. 135MB per image seems WAY beyond what is necessary to maintain the quality of these slides, so I would like SOME compression, but don't want to see any clearly visible signs of quality loss. Any words of wisdom welcome.

Previews not Generated for 1024 Preview Size

I created a new catalog, selected the preview size of 1024, medium quality, then imported a bunch of Nikon NEF photos, and converted to DNG. Regardless of whether I render previews on import, or render previews manually, when I scroll through Loupe, I get the Loading message. When I look at the previews folder for the catalog, the preview for a sample photo changes from about 250KB to 1.5MB after I get the Loading message.
When I create another catalog and select a preview size of 1440, it works as expected and there is no delay scrolling though Loupe mode. The previews seem to be, however, about 400KB in size.
So there seems to be 2 issues. One is that the 1024 previews aren't generated until the photo is viewed, and the other is that the size of the preview is disproportionate.
Anyone else see this?
System is Windows XP SP3, Lightroom 3.2.
John Gregson

John,
The following may give you a better idea as to how Lr handles previews http://forums.adobe.com/thread/358026?tstart=0 and http://forums.adobe.com/thread/358039?tstart=0

Standard Preview size/quality Lightroom 1.1. (how and what)

I'm working on a Macbook pro, with hi-res 17" screen 1920x1200. In most manuals, tutorials etc. it says that you can "set the standard preview size fitting for your screen".
I'm looking for some more background info on the standard preview, to decide which setting to use(if somebody has other criteria to keep in mind please do say so):
1) What is the difference in size of files for the different combination of options (pixel/quality). Does somebody have a list.
2) What is the actual difference in the quality options
3) In which modules is the preview size used (also in development and slide show?)
4) Are they also used to generate the thumbnails from? If so, does a higher standard preview size reduce the performance in library mode because it as to shrink bigger files for these thumbnails?
5) what happens if I would use the smaller, let's say 1440 preview and then decide to view the picture full-size, in library or slide show
6) What would be the size (in pixels) on the normal main window in lightroom on my 1920x1200 screen. if it is about 1440 (might take that one)
Last question of course: What standard preview size / quality should I use on my 1920x1200 screen??
Thanks in advance for all your thoughts!

As to standard preview size and quality, try 1440 and 1680 and Med and High quality and see what you like best. You will probably choose 1680 size for your screen running at 1920x1200. That will let you run LR full screen where the image size will be close to the full size of your monitor. You can try 1440 too but I doubt that you will see any performance improvement. I have tried both sizes on my 1600x1200 monitor and I see no difference in quality or speed.
Try both Med and High quality and see if you notice any difference in your preview quality or speed. High will make your preview folders bigger which might be a factor if you have limited hard drive space.
Don't think preview size has anything to do with thumbs. Standard previews are separate from 1:1 previews so you can always zoom in and LR will generate a full size preview.
In short feel free to experiment with various settings in LR. Good way to learn the program and you will know what works best on your particular computer.

DNG conversions not opening

I dusted off an old Toshiba laptop that has a copy of CS4 Photoshop and the newest DNG Conversion software (v8.8). Pointed the DNG at a folder of RAW files (Olympus ORF), converted them, opened them in ACR and saved the files that are now .dng files in Bridge...but CS4 won't open them, says it doesn't support this file type. How can Adobe Photoshop not open an Adobe file type? I thought DNG made all RAW files backward compatible for Photoshop going back to the beginning of time. Any ideas, suggestions, solutions?

I got a couple of sample raws and converted them on the mac side using the 8.8 dng converter and they seem to open on both photoshop cs4 on mac and windows xp
Did you check to make sure both your photoshop cs4 versions have camera raw installed and are updated to camera raw 5.7?

DNG Conversion Fails in Camera Download

I've been using Photoshop CS4, Bridge and ACR for about a year. I was sold on the Adobe rationale for converting to DNG and have been doing so using the convenient check box on the Photodownloader screen. It has worked fine the entire time - until now. Suddenly that no longer works: although the DNG conversion box is checked Bridge only downloads the raw NEF files and reports at the end that it the DNG conversion failed on all of the photos that were downloaded.
So - here is what I've tried:
- Rebooted my Windows XP computer ( dual core - which has 4GB of RAM). Same results - no conversion
- Reinstalled Photoshop CS4 - and everything on the disk. Same results - no conversion
- Downloaded version 5.7 of Camera Raw (just found out there is a 5.9). However that seems to only update camera profiles - and doesn't change the version that displays on the Camera Raw preferences menu: 5.0.0.178. Same results - no conversion.
- Finally I downloaded the free DNG converter. It works, but I would much prefer to have the download program work
Any clues to solving this will be greatly appreciated.

Film4Now wrote:
…version 5.7 of Camera Raw (just found out there is a 5.9)…
??? !!! Where?
Film4Now wrote:
… the version that displays on the Camera Raw preferences menu: 5.0.0.178…
That proves you did not install 5.7 correctly and you failed to remove the old 5.0 plug-in.
Wo Tai Lao Le
我太老了

Preview size question

Right now Preview size is set at Half Size and slider all the way to the left. Lowest quality I guess. This all in Aperture 2.1.1 preferences.
It takes forever to update previews. I shoot D300 NEF.
Is there a way to turn off previews? Or make them as small as possible? I import the photos on the MBP hard drive.
So I need Previews? I do not use the other iLife apps.
Anything to make Aperture faster is what I'm looking for.

No it says Previews next to the spinning pie chart as it's updated. I see thumbnails too.
My settings
If I make complex adjustments to a photo, I can wait for quite a while as the preview updates before I can do anything else. If I could turn off previews I could literally do my work in half the time.

Preview size & quality settings

Although I have been using LR for many months I am still confused as to what to set my import settings to when it comes to previews. Standard or 1:1? What quality settings? Can anyone enlighten me on best practices?

>... my import settings to when it comes to previews. Standard or 1:1?
Standard Size previews are of your choosing: 1024, 1440, 1680 and 2048. You set these in the catalog settings "File Handling" tab. Also, you can set the quality to Low, Medium or High. You could also think of the Standard Size as that which most closely matches you screen size.
1:1 Previews are previews that match the dimensions of the image and are generally much larger than the Standard Size previews. e.g. from a 10MP Nikon D200 the size is 3872*2592.
The implications of your choices are as follows:
- The larger the preview size that you choose, the slower the import
- Larger previews take more disc space in your .lrdata folder, specifically the thumbnail-cache file.
If you are going to import a large number of photos, that you may later cull prior to doing any develop work, then you could choose Standard Size previews, with a low (1440) pixel size, Medium Quality. Import should then be fast. After you have eliminated photos that you do not wish to keep, you could use the Library ->Previews -> Render 1:1 Preview, if you wish to generate full-size previews of the selected pictures. Again, this may take a significant amount of time, depending on how many photos you select.
When you go to Develop module, Lightroom will automatically generate a 1:1 preview of the selected photo. So if you are not concerned about a slight delay while Lighroom generates 1:1 preview in Develop module, you could stay with Standard Size previews for import.

Standard Preview Size/Preview Quality

This may be a silly question, but in Library mode, under Edit>Catalogue Settings>File Handling, you have options under Preview Cache for 'Standard Preview Size' (1024/1440/1680/2048/2880 pixels) and Preview Quality (High/Medium/Low)... but what do these settings actually do; I've tried changing them & not noticed and difference??

Les_Cornwell wrote:
Thanks again Rob
You bet .
Les_Cornwell wrote:
I've tried all the different size options, namely 1024 through to 2880 & low/Medium/high and none make any obvious difference at all.
So are previews only created as required when you view a picture in full screen mode or does LR create a preview for all your files?
Every image you look at in Library module comes from the (library) previews, there are up to 8 possible jpegs:
* a tiny thumbnail in root-pixels.db
* up to 7 jpegs ranging from small to 1:1 in the "preview pyramid" (each smaller is half the dimensions of it's bigger sibling).
Try this with a 10 photo test catalog:
If you have a big monitor and set standard preview size to 1024, then (with Lr closed) delete all previews, then restart Lr and wait for all the "..." indicators to be extinguished (indicating standard previews have been built), then step from photo to photo in loupe view with all panels collapsed (loupe view "real-estate" maximized), you should see "loading" indicator, since it needs a bigger preview than you've got built. What it will do then is build 1:1 previews and all the smaller ones along with it, which is suboptimal from a performance point of view. If you try and zoom in to 1:1 after the "loading", there will be no additional loading, since 1:1 previews were already built.
Then, repeat the test with preview size at max - no loading indicators, right? (when stepping in loupe view after standard previews have finished being built, I mean). Except now if you try to zoom in there will be "loading", since 1:1 preview were not required to display the loupe view, they will need to be built for the zoomed (1:1) view.
The only difference between big enough and too big will be an ever-so-slightly greater lag when stepping in the loupe view and no 1:1 preview exists (when preview is too big I mean), since it's loading a bigger standard preview than is actually needed. Reminder: if preview is not big enough, there will be an ever-so-slightly bigger lag when stepping in loupe view too (e.g. vs. just big enough), since it's using the 1:1 preview instead of standard (which wasn't big enough). So, tester beware... (somewhat counter-intuitively, in some cases, it will be faster loading a preview when settings are, in general, too big, because it can get away with loading the next size down, which is an even better fit, e.g. if image is cropped just so - all of these little nuances make it especially tricky to test & evaluate, so consider doing initial tests using uniform-size uncropped images, to reduce the number of variables - it's confusing enough as it is ;-}).
Note: as previously mentioned, there is considerable complexity (and bugs) in the preview system, and I may not have described it perfectly, so it wouldn't surprise me if your results were not exactly like that, but I just went and retested on my system, and what happened is exactly as I described above (win7/64), as I read it anyway...
Regarding quality, you should see difference in some photos not others, but ONLY if it didn't resort to the 1:1 preview which may be higher quality than the standard and is independent of the standard quality setting. (I think somebody may have stated that you'd need to zoom in to see differences in standard preview quality settings, but that is wrong - the only way to see differences in standard preview quality settings is if you are in fact viewing standard previews, which you aren't when zoomed in to 1:1, and anyway it can be ellusive - see paragraphs above...).
PS - If you want to compare jpeg quality of standard previews, one way is to export them using PreviewExporter. Again, it's tricky, since you need to assure you aren't exporting a scaled down version of the 1:1 instead of a true standard preview. After exporting you can compare outside Lightroom, so you don't have the "preview of a preview" issue going... I use Beyond Compare by Scooter Software for doing objective comparison of like-sized jpegs, but you can compare subjectively using any ol' viewer, e.g. as built into OS.
Too much?
UPDATE:
Les_Cornwell wrote:
does LR create a preview for all your files?
No - they are created on an as-needed basis (thus the reason we hear many complaints about how stale or non-existent previews should be built in the background, to minimize "loading" in library module, e.g. after making dev changes to a large bunch), but note: standard previews may be considered "needed" when thumbnail is in view in grid or filmstrip (but not considered needed if thumbnail is off-screen, even if existing in filmstrip and/or grid).
R
Message was UPDATED by: Rob Cole

Speed-up? - Force a rebuild of Preview Size

Folks
Many people say they experience an increase in speed by having smaller previews. The default Preview size, in 1.5, as set in Preferences under 'Limit Preview Size' is 'Don't Limit'.
If you alter this setting to a smaller setting it does not alter the size of your existing Previews. Some folks suggest throwing away all your Previews and starting again. However - Tech article 304345 suggests an easier/better way
Aperture: Previews do not update after changing Limit Preview Size Preference
Solution:
Issue or symptom
After you change the Limit Preview Size setting in Aperture's Preferences, existing previews are not changed, even if you choose Images > Update Previews.
Products affected
Aperture 1.5
Solution
Changing the Limit Preview Size setting does not mark existing previews as out of date. In order to force existing previews to be regenerated using a new size setting, select the desired images, press Option and choose Images > Generate Previews.

Is there a way to easily tell which pictures have unwanted preview sizes? I started building previews (36,000 pictures)with the aperture default setting (unlimited size) and a day-and-a-half (approximately 24,000 pictures) later switched to the size recommended for my display. Aperture is definetly running slower than before I updated to 1.5. If there isn't an easy way to identify and resize the "unlimited size" photos, am I better off just deleting all previews and rebuilding them from scratch, or should I just rebuild as needed for purposes of ilife integration? I like the idea of being able to view all pictures in my Aperture library for purposes of using in other applications but if it is in fact slowing down Aperture I will happily rebuild.
G5 2.3ghz, 23 inch HD cinema display Mac OS X (10.4.8)

Larger font preview size

How do I change the font preview size in the drop down font preview list in Adobe inDesign cs6?

It's in the Type section of the prefs...

Preview size for at 22 inch monitor?

Hi, I have just read some posts suggesting that changing the pixel dimensions for a specific monitor can help performance as far as rendering images is concerned. I have a 22 inch Samsung monitor, what would be the optimum pixel dimensions. At the moment it is set at default 1440 pixels, should I change it, and if so to 1680 or 2048? I suppose I could experiment, but is there an "optimum"!
As always
Thanks

The standard preview size should be set to match as closely as possible to the resolution at which you use your monitor. Therefore, there was some relevance to the question regarding the native resolution of the monitor as simply stating the size of the monitor does not dictate the resolution at which it operates. In my case, I have a 26 inch monitor, but the important information is that I have it set at its native resolution of 1900x1200. Therefore, I set the standard preview size to the closest resolution without exceeding it, which in this case will be 1680. Note that the standard preview size has nothing to do with any zoom factor as applying any zoom factor, even a 1:1, will quickly exceed the maximum standard preview size available of 2048.
Hope this helps!

LR and DNG conversions from NEF

Just received a batch of Nefs and corresponding dng conversions from a client. I immediately noticed that there was a serious white balance difference between these pairs--LR shows the Nefs at 5600 and the dngs at 7100. Is this typical. I have worked with dngs a few times, but this is the first set of images that I have seen with side by side conversions. Is this typical? Neither the dngs or nefs have been previously edited. I don't normally work with dngs--only when a customer insists.
Very curious about this WB difference. Any explanations from the color gurus here? TIA

I was aware that the numbers were relative and would likely be different, but in this case the images are visibly very different--I just gave the numbers to indicate what LR saw them as. When the difference is between 5600 (NEF) and 7100 (dng) one sees a big difference between the cool NEF and the warm dng on the screen. This difference is seen systematically in a batch of about 75 images. LR shows no metadata differences except the WB reading. Could this have resulted from a dng conversion in an older dng converter?

DNG Conversion - preview size

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