Benefit of DNG Lossy?

I just watched a free tutorial (well, several!) on Lynda.com regarding LR4 new DNG Fast and Lossy.
I understand that the Lossy DNG retains more information versus a jpeg. But if most of the world is using jpeg - exporting a Raw to Lossy will just finally result in converting to jpeg anyways, for print or posting on the web.
Benefits of Lossy, and how is it to be used in our workflow?
I never use DNG... now there is the DNG Fast... do many of you folks import your photos from Raw to DNG? Same benefits as working with Raw files?
the "DNG Fast allowing us to work 8X faster in the Develop Module" seems a compelling reason to experiment(!)
Thanks for your help

Up until now, DNG saved a little space on disk with its lossless compression, and it had the advantage of keeping XMP data internally instead of in a sidecar file. It also, in recent incarnations, keeps a checksum of image data, which allows easy computer checking of image corruption. Those are all relatively minor advantages.
The Fast Load data, if it works as advertised, is a compelling reason to convert all one's raw files to DNG. On that basis alone, I'll do it.
On a different thread, Eric Chan talks about lossy DNG compression. He claims that one of the ways it was tested was to create a lossy DNG and pass it and it's parent raw to Photoshop and see if people can tell which was which. Kind of a blindfold taste test. If you can't tell whether it was lossy-compressed or not, and it gives you the processing latitudes of a raw file, why not use it? The space savings are dramatic.
For somebody like me for whom an 8 x 10 print is big, lossy compression is a no-brainer except for 5-star images, of which I have maybe two.
Hal

Similar Messages

DNG lossy details - I found out

Dear reader,
my first step was to create color-filter-array dng files, but in lack of knowledge about windows development and the superior dng specs (missing free available TIFF/EP standard I found out later), I developed based on libtiff (see Listing 1 )
It uses IEC-sRGB XYZ->RGB color matrix.
Then I used Adobe DNG Converter 8.2 to get DNG lossy. There I found out that almost always in the opcodes (see Listing2) (extracted with tiffdump -m300 -o offset lossy.dng | perl Listing2.pl ) (for availbale subifd-offsets, do tiffdump | grep -i ifd )
there is following transformation:
linear = 0.0625*perceptual + 0.9375*perceptual³
(reverse function:
sub perceptual {
    my $linear=shift;
    my $y=$linear;
    my $term=(360*$y +sqrt(5)*sqrt(1+25920*$y**2))**(1/3);
    return
        -(    1 /
            (5**(1/3)*$term)
        +
        $term /
        5**(2/3)
    )/3;
... or something with shrinked range to match tighter range of input values (than 0..1).
So, assuming 12 bit linear raw, you get an 1:1 mapping near zero (4 bits lost from 12 to 8 bit, but *16 due tue perceptual() transformation, and a 1:46 mapping near one (4 bits lost = /16, additional factor 2,8 approx due to differentiation of linear = ... ( see above ) ).
The afterwards jpeg compression uses no subsampling and these quantization tables:
qtable 0: 2 2 2 2 3 4 5 6 2 2 2 2 3 4 5 6 2 2 2 2 4 5 7 9 2 2 2 4 5 7 9 12 3 3 4 5 8 10 12 12 4 4 5 7 10 12 12 12 5 5 7 9 12 12 12 12 6 6 9 12 12 12 12 12
qtable 1: 3 3 5 9 13 15 15 15 3 4 6 10 14 12 12 12 5 6 9 14 12 12 12 12 9 10 14 12 12 12 12 12 13 14 12 12 12 12 12 12 15 12 12 12 12 12 12 12 15 12 12 12 12 12 12 12 15 12 12 12 12 12 12 12
Perhaps this coud clear some things.
Kind regards,
Listing 1:
/* CameraProfile - erforderl? */
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include "tiffio.h"
#include <math.h>
#define TRUE -1
/* siehe http://www.remotesensing.org/libtiff/addingtags.html */
/* siehe auch http://www.opensource.apple.com/source/tcl/tcl-87/tcl_ext/tkimg/tkimg/libtiff/tools/tiffse t.c */
static const TIFFFieldInfo xtiffFieldInfo[] = {
    { 33421, -1,-1, TIFF_SHORT,    FIELD_CUSTOM, TRUE, TRUE, "CFARepeatPatternDim" },
    { 33422, -1,-1, TIFF_BYTE,    FIELD_CUSTOM, TRUE, TRUE, "CFAPattern" },
    { 50706, 4, 4, TIFF_BYTE,    FIELD_CUSTOM, TRUE, TRUE, "DNG_Version" },
    { 50708, -1,-1, TIFF_ASCII,    FIELD_CUSTOM, TRUE, TRUE, "DNG_UniqueCameraModel" },
    { 50721, -1,-1, TIFF_FLOAT, FIELD_CUSTOM, TRUE, TRUE, "ColorMatrix1" }
#define    N(a)    (sizeof (a) / sizeof (a[0]))
uint16_t quant16(double x) { return (int)(65535*x+0.5); }
/* Quote from Wikipedia:
The numerical values below match those in the official sRGB specification (IEC 61966-2-1:1999) and differ slightly from those in a publication by sRGB's creators.[2] Note that these linear values are not the final result.
[2] Michael Stokes, Matthew Anderson, Srinivasan Chandrasekar, Ricardo Motta (November 5, 1996). "A Standard Default Color Space for the Internet – sRGB, Version 1.10". http://www.w3.org/Graphics/Color/sRGB
float iec61966_2_1_1999_XYZ_to_sRGB_D50[]={
3.2406, -1.5372, -0.4986,
-0.9689, 1.8758, 0.0415,
0.0557, -0.2040, 1.0570};
int main(int argc, char **argv)
    uint8_t ver[]={1,4,0,0};
    int16_t repeat[]={2,2};
    uint8_t pattern[]={0,1,1,2};
    int width=2048, height=4096, format;
    uint16_t *cfa_row;
    double minc[3]={ 9e99, 9e99, 9e99};
    double maxc[3]={-9e99,-9e99,-9e99};
    double xx,yy,d;
    int x,y, c;
    double v;
    FILE *fw;
    TIFF* tif = TIFFOpen("out.dng", "w");
    cfa_row = malloc(width *16/8);
    /* Install the extended Tag field info */
    TIFFMergeFieldInfo(tif, xtiffFieldInfo, N(xtiffFieldInfo));
    TIFFSetField(tif, TIFFTAG_IMAGEWIDTH, width);
    TIFFSetField(tif, TIFFTAG_IMAGELENGTH, height);
    TIFFSetField(tif, TIFFTAG_BITSPERSAMPLE, 16);
    TIFFSetField(tif, TIFFTAG_SUBFILETYPE, 0);
    TIFFSetField(tif, TIFFTAG_ORIENTATION, ORIENTATION_TOPLEFT);
    TIFFSetField(tif, TIFFTAG_PHOTOMETRIC, 32803);
    TIFFSetField(tif, 33421, 2, repeat); /* obwohl immer 2, muss oben -1 stehen sonst speicherfehler*/
    TIFFSetField(tif, 33422, 4, pattern);
    TIFFSetField(tif, 50706, ver); /* aber hier nicht -1 ?! */
    TIFFSetField(tif, 50708, "dng.c");
    TIFFSetField(tif, 50721, 3*3, iec61966_2_1_1999_XYZ_to_sRGB_D50);
    for(y=0; y<height; y++) {
        d=yy=1.0*(y/2)/((height-1)/2);
        for(x=0; x<width; x++) {
            xx=1.0*(x/2)/((width-1)/2);
            c=1;
            if(x%2==0 && y%2==0) c=0;
            if(x%2==1 && y%2==1) c=2;
            v=0;
            if(x==0) { printf("yy=%f d=%f\n",yy,d); }
            switch(c) {
                case 0: v=65535.0*d; break;
                case 1: v=65535.0*d; break;
                case 2: v=65535.0*d; break;
            cfa_row[x]=(uint16_t)(v+0.5);
            if(v<minc[c]) minc[c]=v;
            if(v>maxc[c]) maxc[c]=v;
        TIFFWriteScanline(tif, cfa_row, y, 0);
    TIFFClose(tif);
    for(c=0; c<3; c++) {
        printf("%f..%f\n", minc[c], maxc[c]);
    return 0;
Listing2:
#!/usr/bin/perl
use strict;
$|++;
# big-endian!
# tiffdump -m 300 -o 63248 DSC_1572.dng |perl opcodes.pl
#51009 (0xc741) UNDEFINED (7) 256<00 00 00 0x3 00 00 00 0x8 0x1 0x3 00 00 00 00 00 00 00 00 00 0x44 00 00 00 00 00 00 00 00 00 00 0x4 0x60 00 00 0x6 0x90 00 00 00 00 00 00 00 0x1 00 00 00 0x1 00 00 00 0x1 00 00 00 0x3 00 00 00 00 00 00 00 00 0x3f 0x6e 0x54 0x1e 0x54 0x1e 0x54 0x1e 00 00 00 00 00 00 00 00 0x3f 0xac 0x6e 0xdc 0x6e 0xdc 0x6e 0xdc 00 00 00 0x8 0x1 0x3 00 00 00 00 00 00 00 00 00 0x44 00 00 00 00 00 00 00 00 00 00 0x4 0x60 00 00 0x6 0x90 00 00 00 0x1 00 00 00 0x1 00 00 00 0x1 00 00 00 0x1 00 00 00 0x3 00 00 00 00 00 00 00 00 0x3f 0x79 0xc9 0x19 0xc9 0x19 0xc9 0x1a 00 00 00 00 00 00 00 00 0x3f 0xb8 0x2c 0x88 0x2c 0x88 0x2c 0x88 00 00 00 0x8 0x1 0x3 00 00 00 00 00 00 00 00 00 0x44 00 00 00 00 00 00 00 00 00 00 0x4 0x60 00 00 0x6 0x90 00 00 00 0x2 00 00 00 0x1 00 00 00 0x1 00 00 00 0x1 00 00 00 0x3 00 00 00 00 00 00 00 00 0x3f 0x6e 0xc 0x1e 0xc 0x1e 0xc 0x1e 00 00 00 00 00 00 00 00 0x3f 0xac 0x2b 0x5c 0x2b 0x5c 0x2b 0x5c>
my @plot;
sub op {
    my $s=shift;
    my $opcodeId=unpack "N", substr($s,0,4);
    my @ver=unpack "CCCC", substr($s,4,4);
    my $flags=unpack "N", substr($s,8,4);
    my $vsize=unpack "N", substr($s,12,4);
    print "$opcodeId - v".join(".",@ver)." flags=$flags vsize=$vsize\n";
    $s=substr($s,16);
    print "   ";
    if($opcodeId==8) {
        my @v=unpack(("N"x9), substr($s,0,4*9));
        $s=substr($s,4*9);
        print join(", ", @v);
        my $degree=$v[$#v]; # 0..degree
        print " degree=$degree ";
        my @coeff=unpack(("d>"x($degree+1)), substr($s,0,($degree+1)*8));
        $s=substr($s,($degree+1)*8);
        my $out="";
        for(my $c=0; $c<=$degree; $c++) {
            if($coeff[$c]==0) { next; }
            $out.=sprintf "%+g*x**$c", $coeff[$c];
        print $out;
        push @plot, $out;
    else {
        die "$opcodeId ?\n";
    print "\n";
    return $s;
sub pre_op {
    my $s=shift;
    $s=~s/0x//g;
    $s=join("", map { chr(hex($_)) } split / +/, $s);
    my $n=unpack "N", substr($s,0,4);
    print "$n opcodes\n";
    $s=substr($s,4);
    for(my $i=0; $i<$n; $i++) {
        $s=op($s);
while(<>) {
    chomp;
    if($_=~/^510(08|09|22)\b/) {
        if($_=~/<([^>]*)>/) {
            pre_op($1);
    elsif($_=~/^50712/) { print "LinearizationTable\n"; }
    elsif($_=~/^5071[34567]/) { print "Black/WhiteLevel\n"; }
print join(", ", @plot)."\n";

You can get back 3.6 here: http://www.mozilla.com/en-US/firefox/all-older.html

DNG lossy compressed - the workflow side

The technical side of DNG has already been discussed in other threads. I want to focus on the workflow side here. Viktoria and I have talked about this previously but I wanted to bring it into this forum.
The task is to use lossy compressed DNG files for (way faster) uploading to a service. Service works on the files and sends back a new Lightroom catalog. What we're hoping for was a possibility to import the new settings from that returned catalog and have them applied to the RAW files in the local source catalog.
Victoria though she had tried it once and it worked, but I was not able to confirm this. When I "Import from Another Catalog", this is what I end up with after I imported the altered DNGs. They now are side by side in the catalog, the original, unaltered NEFs and the altered (black & white) DNGs.
Also the field "Changed Existing Photos" in the import dialog was greyed out and said "(none found)". Which is actually kinda expected behavior, isn't it? If you import the same image in a different image format (NEF vs DNG) then Lightroom keeps both as individual files.
Is the necessary workflow for this to use DNG locally as well and ditch the NEFs? Can someone help and elaborate on this functionality?

Yes, and it might be a good reason for switching to a DNG workflow. If the DNGs and NEFs have matching file names, you could us my Syncomatic plugin to copy most adjustments .

DNG 1.4 Lossy Compression Bit Depth

Hi,
The SDK have not been yet released but I'm wondering is the DNG lossy compression bitdepth converted to 8bit, converted to something else, or is it keeping the original bitdepth ?
I'm wondering cause I'm mainly using DNG as the format for my 35mm scanned pictures. I did a short test using the lossy compression and it seems impressive, my 185Mb file is reduced to 10.8Mb, and there is only a slight loss. However, as I often to radical color correction in lightroom, alot of tweak in the shadows, I just want to make sure I'm not that suddendly, my corrections will not be apply to a 8bit depth and that I will get a posterized result.
Thanks.

The spec and SDK are available here:
http://www.adobe.com/dng
Yes, the lossy compressed images are in 8 bit. Whether or not you'll get posterization will depend on the circumstances of the original capture, as well as how strong of a correction you apply. As you say in your case, you tend to make strong color corrections, so you'll simply need to do some more testing to determine whether or not there will be any problems. Unfortunately I can't think of any other rules of thumb or shortcuts other than direct evaluation with your own eyes.

ACR 4.5: Improved DNG 1.2 compatibility

Elsewhere, Thomas Knoll said ACR 4.5 (currently in Beta status) was the first ACR version to fully implement the new DNG 1.2 specification.
Are there any disadvantages to expect when
i not
re-converting our raw files to DNG with the DNG Converter 4.5? What if the original raw files aren't around anymore; does it make sense to push DNG 1.0 or 1.1 files through DNG Converter 4.5?
-- Olaf

No, there are no advantages of reconverting from the original raw files vs. just "upgrading" the old DNG files to new DNG files by running them through the DNG converter again.
The primary benefit of DNG 1.2 at this time the MD5 hash of the raw data that is maintained in the DNG file. This allows Camera Raw 4.5 to detect and warning about image damage due to disk or memory errors if the DNG files gets corrupted sometime after it was first created.
The main advantage of DNG 1.2 in the future is support for the new camera profile color model, and the ability to embed multiple camera profiles in the DNG file. But that benefit requires some actual profiles that use this new model, which are not available just yet...

Lossy DNG shows strong visible differences but JPG not, is this a bug?

Hello,
I tried out the lossy DNG format with a lot of pictures.
For most pictures I can't find any visible differences.
But I found also some pictures with very noticible visible differences between lossless and lossy DNG.
It seems that the lossy DNG format has problems with dark pictures with small light sources for example
the stars in the dark sky or the red lights of an aeroplane in the dark sky.
I have an example where you can see red security lights of a great antenna on top of a mountain.
Surprisingly with this extreme example the JPG versions looks much better as the lossy DNG version of my source lossless DNG.
Here is the cropped JPG from the lossless DNG (file size 10877KB):
Between this JPG and the lossless DNG file is no visible difference.
And here a JPG from the lossy DNG (file size 13261KB):
Between this JPG and the source lossy DNG file is no visible difference.
The source of both DNG files was a NEF File from a Nikon D7100.
Also interessting is, that for this excample the file size of the lossy DNG is greater than the lossless DNG. This seems crasy IMHO.
I was very surprised, that JPG result is is much better than the lossy DNG for this case.
Perhaps there is a hidden bug in the lossy DNG conversion process.
I hope Adobe can look in to this. If you need the original NEF file let me know.

JimHess wrote:
I thought about responding the other day, but decided my remarks wouldn't help you. And they still won't because I'm going to give you my personal opinion about lossy DNG. I don't think it is intended for your master "important" images. I watched a video on Adobe.tv about this, and the example that was given was, suppose you have taken pictures at a wedding. Perhaps you have 2000-3000 images, 500 of which are keepers that are really good. You don't want to get rid of the other bunch but want to save space. So those would be the images that you would convert to lossy DNG. I mean, let's be realistic about this. You can't throw away data and hope to still have full raw quality. That isn't the idea behind the format.
Personally, I think converting to DNG of any sort as a workflow routine is frivolous and unwise. I know a lot of people routinely download and convert, and then they don't have copies of their original raw images. Yes, I know, the DNG files contain all the original raw image data. But not all software will read those DNG files. For example, I use Nikon cameras. The cameras shipped with ViewNX 2. It's not a very useful program, but has a couple of features that I like to use once in a while. But it won't open the DNG files. And if I have converted and then discarded the original NEF files, I can't use the software. With my cameras there is only a 15-20% savings in space. The tutorial I watched indicated that the lossy DNG files would load in Lightroom up to 8 times faster. I haven't used a stopwatch, but if anything the DNG files take longer to load than the original NEF files.
The only benefit I see to converting to DNG is if I have a file from a camera for which I don't have native support because my software is older or not up-to-date. I know this hasn't helped you. But maybe it will stimulate some conversation and you'll get a more enlightening opinion from someone else.
First of all I want to use lossy DNG because I want save space.
Second, I have no extra XMP-File for every image.
If I can't see any visible difference between a lossy DNG and a lossless DNG, then I have no problems with losing some data.

NEF --- DNG Conversion: Is it lossy or lossless?

I was recently reading on a Nikon Forum where a writer stated that some data is lost when converting to DNG in Lightroom. His comments follow.
I'd appreciate if some of the seasoned experts here would offer an opinion, and hopefully, a rebuttal. Thanks for any information you can share on this subject
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Every compression algorith is flawed if a single bit is lost and the original can not be recreated. Since the DNG converter must know about your camera model and it actually converts the NEF into an image before compressing the image, AND you can not, after converting to DNG convert back to original NEF, it is to me obvious that it is indeed a lossy compression, not just 'simple' data compression like zip, tar or whatever other type of data compression you want to compare with, which is truly lossless.
The Nikon lossless compression works entirely on data compression principle, preserving every bit and recreating every bit of data when you edit the raw image, and that can not be done once the image is converted to DNG. That is why many people, who use DNG, also preserve the original NEF, which in my opinion, is a totally pointless work flow. The only reason I can see to use DNG is the ability to share the image with somebody else who is not able to edit NEF, but I might as well use TIFF in that case.
The DNG converter must have knowledge of the camera model concerned, and be able to process the source raw image file, including key metadata to be able to convert and compress. A real lossless compression algorithm NEVER looks at the contents of the data because it is totally irrelevant for the converter to know what type of data you convert and try to compress, since it is based on mathematical patterns and statistics only.
I look at DNG like I look at PDF. A Word document, especially with photographs in it, can be converted to PDF and it may look like you have not lost anything, but yes, you have lost a lot actually and you can never ever recreate the original Word document with the same quality like you have had in your original.
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

727737757 wrote:
The only reason why I convert NEF to DNG is that I like *not* having sidecar files.
A perfectly valid reason to convert to DNG, in my opinion.
And if you are using in Adobe software, you will notice no ill side-effects (e.g. no data loss) whatsoever, so I think you can have full confidence..
But to offer a little more explanation:
The DNG converter needs to know the camera model because it's doing a lot more than "zipping" up the raw data. e.g. it's also creating a camera profile, and interpreting white balance..
Obviously, lossy compression is, well, lossy - I was talking about the lossless compression of raw data, which is 100% perfectly lossless (not a single bit is dropped..).
But if you open a NEF in Aperture, you can see the focus point. If you open the converted DNG, you can't. Not because the focus point information is not in the DNG file, but because it's not in a prescribed place where Aperture can find it - so you could say it's "lost" for practical purposes, although that's not how I think of it.
Cheers,
Rob

Info on lossy DNG?

The idea of a (slightly) lossy, but full dynamic range, compressed image format is excellent, and long overdue. It seemed up to now that JPEG XR (previously HD Photo) would be the best choice, if only anyone agreed to use it. I was hoping LR would soon offer import/export of this format. The main advantage of a format such as this is much reduced storage space, full dynamic range preservation for further editing, and minimal loss of spatial detail.
It seems the new support for lossy DNG in LR beta 4 is a step in the right direction: I could convert all my raw files to lossy DNG on import, save roughly half the storage space (very important in online backup), and still have close to original fidelity, and full dynamic range, for processing.. And in briefly playing with it, it does look promising. But I can't find any real information on exactly what this format does, and I have roughly 98 questions about it, of which I'll ask only 4 here
Is the image data linear / demosaiced, or original sensor format?
Are exported images the edited / developed pixels, or the original pixel values, with the edits saved only in the CRS metadata?
What is the compression algorithm? JPEG (DCT), wavelet, or some other Adobe tech?
What is the quality loss of this compression, and why is there no quality / size selector in the export dialog?
Answers or pointers would be highly appreciated.

Hi Sandy,
Indeed, data is data, but I think the degree to which one can process the data effectively will depend on its state. Here are some concrete examples where I feel having the scene-referred data makes a big difference:
1. Staying in the original camera space primaries (as opposed to storing data that's already transformed to a canonical space, like Adobe RGB or sRGB, like most camera JPEGs).
I see two advantages. One is that since the data is not yet mapped/clipped to a smaller gamut space, the raw converter can then perform smooth gamut mapping (under user control) to determine how saturated colors are handled. For example, red flowers that are often clipped in camera JPEGs are often not clipped in the original camera primaries (they only become clipped during the raw-to-output gamut mapping process, unless one takes care to avoid the clipping). A second advantage is that chromatic aberration correction tends to work a lot better. This is because of the spectral separation between the primaries. (Once they are "mixed" into sRGB or Adobe RGB primaries, it is much harder to perform the correction.)
2. Changing the white balance. Yes, one can change the WB for any output-referred image, too, but since the tone curve used to render that data is often unknown, it is much harder to get good WB results without color crosstalk along the tonal range (e.g., light areas may appear neutral, but midtones will then take on a cast, or vice versa). Furthermore, most output-referred data is already white-balanced, and any channels that become clipped in the process cannot be recovered if one wants to adjust the WB (see previous item on gamut mapping).
3. Noise reduction. Of course, one can always do noise reduction on any image data format or type. However, having (mostly unprocessed) scene-referred data establishes a much better mapping to physical noise models (e.g., how noise varies as a function of exposure), which we use to drive to the noise reduction algorithms.

Why does DNG Converter insist on lossy conversion?

I use DNG Converter to convert RW2 files to DNG so I can work on them in various PP programs.
No matter whether or not I have the "lossy" box checked, DNG Converter insists on doing a lossy conversion.
How can I stop this?
Sample images:
Original RW2 image, with histogram:
DNG image - note loss shown on histogram. There is also posterized banding, although in the small image allowed on this site it is very hard to see.

Thank you for pointing out the problem. Preview from DNG Converter is JPEG.
==================================
UPDATE:
My previous comment, above, is irrelevant.
The preview is JPEG, but I am working with the DNG file. So my original question remains unanswered.
I have found the same issue with RW2 files. I will investigate settings for FastStone Image Viewer (the program I am using for editing). So far I find no options to change treatment of DNG or RW2.

Import RAW files as lossy compressed DNG

In LR4.2, I would like to be able to import my NEF files as lossy compressed DNGs. That option is not available in preferences, so I have to do the import to DNG, then invoke the "Convert to DNG" in the library menu where I can select lossy compression. Why not make that option available on import so I don't have to perform the second step?

JimHess wrote:
Do you really want to import compressed DNG files? They are not really raw files anymore, and they are reduced to 8 bits. That doesn't seem to be a good choice for master images. But the choice is yours, of course.
To be clear, the default settings used for 'Copy as DNG' *does* compress raw data, but without loss (i.e. lossless, not lossy).
I know you knew this Jim, but maybe another reader is not so clear...
PS - I really like the new lossy compressed DNG technology - files behave like raw in terms of editing (white-balance, camera-profile, h/s recovery...), but are much smaller. As long as one realizes that the data will suffer loss, and be pared down to 8-bits (which isn't as bad as it sounds, since it does NOT use the same linear encoding scheme as raw data), then it can be a great option during import, if you don't plan on making big prints...

Convert DNG twice in lossy format, additional loss of quality?

I've got some DNG that by mistake I converted with embedded raw all spread in my Lightroom catalog.
I want to discharge raw, so as Lightroom doesn't allow to sort files by size (whyyy?), the easier solution is to choose all DNGs and convert them again to DNG unchecking "embed raw".
My question is: will this procedure convert twice my image in lossy format resulting in a additional loss of quality or the already compressed image will be untouched?

I've got some DNG that by mistake I converted with embedded raw all spread in my Lightroom catalog.
I want to discharge raw, so as Lightroom doesn't allow to sort files by size (whyyy?), the easier solution is to choose all DNGs and convert them again to DNG unchecking "embed raw".
My question is: will this procedure convert twice my image in lossy format resulting in a additional loss of quality or the already compressed image will be untouched?

How do I convert multiple full sized DNGs to lossy DNGs within Lightroom?

Hi,
When I select multiple DNGs from within Lightroom, and on my mac go to menu>Library>Convert photo to DNG and then choose to convert to DNG with the lossy mode selected, only one of the selected DNGs is converted. How do I convert more at the same time? I have a large library, and I want to convert ~100gb of photos to lossy.
Thanks in Advance!

As far as my own collection goes, I would say I love about 1-2% of my pictures. I would like to use the top 5% for making printed family albums, and I use Lightroom to develop these images. The next 5-10% I would partially process and keep somewhere online at lower resolution, like on flickr. The next 20-40% I would like to keep around in storage, and the rest I trash.
These last 20-40% that I want to keep would be fine as lossy DNGs. I would treat them as JPEGs that have a bit more dynamic range for the future, but as I shoot with a 24mp Nex-7, they are huge, and won't ever be pixel-peeped. I have examined the difference between my 25mb DNGs and the converted 7mb lossy DNGs, and for my uses, they are functionally identical.
The issue is that I need to import them into Lightroom before I rate them. Once I rate my images, I flag the ones I want to work on further, and delete the worst. I would like a way to convert the remaining ones more easily. Of course if I knew which ones were 2nd-rate keepers from the outset, I would import them as lossy DNGs to start with.
I often have 3-4000 images to process after a holiday, so I need a fast method of compressing these DNGs.

Converting DNG to Lossy Compression DNG files in LR4. SWP file?

I am trying to convert some DNG files that were created in LR3 to the Lossy compression in LR4. Lr4 creates a SWP file and the DNG file is not compressed. What is the SWP file and what do I need to do to correctly compress the DNG files?

SWP file is a temporary file. The conversion will take some time, after the file is successfully converted, the SWP file is removed...

Any benefit to convert NEF to DNG

Does anyone convert their NEF (D300 in my case) files to Adobe DNG and then start their workflow?
Or are the NEF's just imported into Aperture and then adjustments are made?
I use Aperture now for a long time. I usually just import the NEF files. I've been using Photoshop CS4 to learn it and have just been sending the NEF file within Aperture to Photoshop. And of course it comes back to Aperture as a PSD file.
I ask because Aperture has a tendency to lag making adjustments. But I noticed Aperture doesn't lag if I make adjustments on the PSD file or a DNG file. Adjustments are in real time.
So I'm thinking of converting my NEF's as the first step of my work flow. Then import the DNG's into Aperture.
I have all of the NIK Software and working with this in Photoshop is 1000% easier in Photoshop than Aperture.
I can't seem to tell any degrading of the NEF converted to DNG. I've done a few now and compare. I can't seem to tell. Pre or post adjustments made in Aperture.
Thanks for any thoughts or opinions.
*There are always two people in every photograph: the photographer and the viewer. - Ansel Adams.*

musicmaker wrote:
Does anyone convert their NEF (D300 in my case) files to Adobe DNG and then start their workflow?
DNG is just Adobe's proprietary attempt to sell the world on using Adobe's RAW conversion format ("DNG," the result of converting camera makers' individual RAW files using Adobe Camera Raw, "ACR"). Adobe benefited greatly with PDF and wants to do the same with RAW DSLR capture.
DNG is not better. In fact most folks (at least the ones not already sleeping with Adobe) will most often find conversions by Aperture and/or individual camera vendors' converters (like NX2) to be visually better than ACR to DNG. However differences among converters are usually slight enough anyway to make RAW-conversion quality irrelevant when compared to workflow.
The conversion of RAW data is different for each individual camera, no RAW converter is best for all cameras, and the results of conversion are a matter of individual taste in any event.
Note that most camera vendors keep RAW algorithms and protocols very secret, so folks like Adobe and Apple do a lot of deduction (some say speculation) when building each camera's RAW converter based on imperfect information. That is why most folks consider Nikon's conversions of NEF files "best;" but unfortunately Nikon's workflow is atrocious.
...is there any significant advantage to converting (to DNG)?
No, there is significant disadvantage in converting NEF to DNG. You would be seriously disrupting Aperture's workflow just to achieve what most folks consider to be less-good RAW conversions.
Some photogs do find significant advantage in first using NX2 to convert Nikon NEF files to TIFF. Others find the differences from Aperture small enough not to justify the weight of the NX2 workflow.
I read the Adobe site regarding how DNG is more a standard then NEF or any proprietary camera file.
That is just disgusting Adobe marketing BS. Nikon was around supporting standards like their lens mount for decades before Adobe even existed. Even if Nikon self-destructed today there will always be plenty of RAW converters for the billions of NEF files already created.
Of course Adobe would love it if the world lowered their standards to some Adobe-defined lowest common denominator, but then we would probably not see the various consistently fast tech advances like the low light performance of the Nikon D3.
-Allen Wicks

How to tell if DNG is raw or not?

Anybody know how to get at DNG metadata, e.g. is it raw vs. linear, lossy, etc..., via plugin I mean.

In case anybody else thinks such info should be available via SDK:
http://feedback.photoshop.com/photoshop_family/topics/lightroom_sdk_please_make_dng_metada ta_available_via_sdk?rfm=1

Benefit of DNG Lossy?

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