Reduce DNG files size when exporting?

[bconner (Bryan Conner)]

Yes, the files are converted with Adobe DNG converter and the lens sharpening sliders are not available. I have contacted customer service about this at least twice, soon after the release of PL6, five months ago and a couple of weeks ago. The first time, in October of last year, I was told that there was a “MakerNote” missing from the dng files created by Adobe DNG converter and DXO would correct the problem in a PL6 update. So, fast-forward to this month and I ask customer service if there is any indication of when it will be corrected and I was told that they don’t have any further information and the developers haven’t specified when it will be corrected.

This in no way is a deal breaker for me, I love PL and am not planning on switching back to Lightroom or Capture One, but I would like to enjoy the small benefits offered by using DNG files with all of the benefits of PL6…including lens sharpening.

[George]

I would like to know what program can read a raw dng that doesn’s support that specific camera.

George

[zkarj (macOS, PLe+FP+VP, Pentax)]

@George

I would like to know what program can read a raw dng that doesn’s support that specific camera.

I don’t personally know of any, but part of the reason DNG exists is exactly this attribute.

From the Wikipedia page on DNG, two of the objectives taken from Adobe literature. (My emphasis.)

• Easy and/or comprehensive exploitation by software developers: to enable software to be developed without the need for reverse engineering; and to avoid the need for frequent software upgrades and re-releases to cater for new cameras.
• Assessment: Software could support raw formats without DNG, by using reverse engineering and/or dcraw; DNG makes it easier, and many software products can handle, via DNG, images from cameras that they have no specific knowledge of.[25] An unresolved restriction is that any edit/development settings stored in the DNG file by a software product are unlikely to be recognized by a product from a different company. (This problem is not specific to DNG).

[George]

I don’t deny the benefits of a universal raw file but some practical examples would be welcome.
Maybe someone out there with a stand alone, no cloud, version of Lightroom that does not support a camera. They could then do a test.

George

[zkarj (macOS, PLe+FP+VP, Pentax)]

@George

If they’ve to support every new camera individual then there’s no new standard, only a new extension.

I have consistently been addressing this assertion that DNG has no value as a standard.

I hope I have illustrated that it has, even if software vendors don’t realise it. Its intent and capability is to describe image data in a device-agnostic way.

[George]

I do agree with the theoretical approach. But I’m looking for the practical approach too. And there it seems something like the emperors clothes.

George

[zkarj (macOS, PLe+FP+VP, Pentax)]

I don’t see why the format gets a knock because vendors don’t want to use it, though. I think it’s a Catch 22. HEIC was far more niche until Apple started using it and now everyone seems to be jumping on. I wager if Canon or Nikon got on board it wouldn’t be an issue.

But here you are… your holy grail of a converter that supports DNG input without a “supported camera” list in sight. Proving it is completely do-able when it makes sense.

This application does not care about the origins of an image hence it freely reads DNG. PhotoLab and every competitor does care about the origins, in order to provide automatic processing of various kinds.

[George]

I don’t know what you mean but Squash isn’t a converter. It just opens an image and shows the embedded jpg like any other program or file browser

George

[zkarj (macOS, PLe+FP+VP, Pentax)]

From the main Squash page…

Squash 3 offers a way to quickly batch convert, and resize images. But that’s not all, apply layered watermarks and filters, rename files, remove or edit private metadata, and so much more.

[KeithRJ (Keith - Perth, Australia - Win11, PL8, VP3, Canon, DJI)]

IrfanView has a very powerful batch processing function and it is free and been maintained for decades. This program is my go-to program for viewing and batch processing and I have been using it for a very long time. It is worth supporting the developer too.

[George]

It doesn’t work on the raw image, only on the embedded jpg, just like Irfanview.
It only converts from one rgb disk file extension to another.

George

[zkarj (macOS, PLe+FP+VP, Pentax)]

@George

It doesn’t work on the raw image, only on the embedded jpg

I don’t know what makes you say that.

I just converted four native Pentax PEF files to DNG using Adobe DNG Converter, wherein I specified that there should be no preview image. I then loaded all four DNGs into Squash and converted them to JPEGs with no issues.

[George]

I don’t know what program you use. You mean https://squoosh.app/?
It just doesn’t read raw files so it can’t convert raw files to rgb-images.
A with the Adobe dng converter converted to dng image.

George

[George]

It seems to be a different program.
Could you do that same experiment with this file?
GW_20120501-000.NEF (13.1 MB)

George

[zkarj (macOS, PLe+FP+VP, Pentax)]

@George

I don’t know what program you use.

Ummm, I mean the program I linked to…

@zkarj

From the main Squash page…

Here is your file converted to DNG with no preview (shrinking from 13.7 MB to 7.8 MB in the process).
GW_20120501-000.dng (7.4 MB)

And the 2.9 MB JPEG produced by Squash.

Interestingly, Squash was able to load your original NEF file but the colours were way, way off. The DNG colours looked fine, as in the JPEG it produced.

[George]

I did edit this image with CaptureNx2, the old version. CaptureNx2 adds the editlist directly to the nef and replaces the embedded jpg with a new one, based on the last edit.
It seems that the dng converter creates its own rgb thumbnail. What you see is an image of only 256x171 pixel.
Squash is using the embedded jpg. I can’t believe it’s converting the nef to rgb with the used edits from CaptureNx2. Squash isn’t converting a raw to rgb but just converting from one rgb disk file to another rgb disk file.
My nef will show you the same image as in Squash: the embedded jpg. Like in all image browsers.

George

[zkarj (macOS, PLe+FP+VP, Pentax)]

@George

Squash is using the embedded jpg.

So I just ran the DNG through EXIFTOOL to see what was within…

---- IFD0 ----
Subfile Type                    : Reduced-resolution image
Image Width                     : 256
Image Height                    : 171
Bits Per Sample                 : 8 8 8
Compression                     : Uncompressed
Photometric Interpretation      : RGB
...
---- SubIFD ----
Subfile Type                    : Full-resolution image
Image Width                     : 3900
Image Height                    : 2611
Bits Per Sample                 : 16
Compression                     : JPEG
Photometric Interpretation      : Color Filter Array
Samples Per Pixel               : 1

Those are the only two image blocks mentioned. The first is obviously postage stamp-sized. The second says is has JPEG compression but you will note it is 16 bit resolution and, importantly, 1 sample per pixel. That means it has not been demosaicked.

I would guess the JPEG compression is lossless JPEG compression.

I then got curious about your original.

---- IFD0 ----
Subfile Type                    : Reduced-resolution image
Image Width                     : 320
Image Height                    : 214
Bits Per Sample                 : 8 8 8
Compression                     : Uncompressed
Photometric Interpretation      : RGB
...
---- SubIFD ----
Subfile Type                    : Reduced-resolution image
Compression                     : JPEG (old-style)
X Resolution                    : 300
Y Resolution                    : 300
---- SubIFD1 ----
Subfile Type                    : Full-resolution image
Image Width                     : 3904
Image Height                    : 2616
Bits Per Sample                 : 12
Compression                     : Nikon NEF Compressed
Photometric Interpretation      : Color Filter Array
Samples Per Pixel               : 1

The conversion did slightly alter the dimensions of the full-sized image (though I cannot figure out why) but has otherwise recorded the full original data.

Then I did a bit more research about the compression DNG uses. Apparently since DNG 1.4 there is an option of lossy compression. I found out that Lightroom’s conversion tool (which uses the same engine as Adobe DNG Converter, of course) has explicit provision to allow lossy compression or not.

So I converted the NEF again, with Lightroom.

Here’s the resulting file content.

---- IFD0 ----
Subfile Type                    : Reduced-resolution image
Image Width                     : 256
Image Height                    : 171
Bits Per Sample                 : 8 8 8
Compression                     : Uncompressed
Photometric Interpretation      : RGB
...
---- SubIFD ----
Subfile Type                    : Full-resolution image
Image Width                     : 3900
Image Height                    : 2611
Bits Per Sample                 : 16
Compression                     : JPEG
Photometric Interpretation      : Color Filter Array
Samples Per Pixel               : 1

Exactly the same, and I therefore conclude the JPEG compression is lossless. Thus, you have a complete original which applications like Squash are able to read… else how else could the JPEG attached above be any bigger than 256x171 pixels?

[George]

I don’t know,yet, what samples per pixel means. I’ve to figure out.
And yes, I mentioned this all the times, Nikon stores a full size jpg in its nef, and a thumbnail.
Some other brands store a fixed lower size in its raw. I’ve some arw files here, raw file 8000x5320, the embedded jpg 1616x1080.
(Un)lossy compression doesn’t change the file size in pixels, it changes disk file size.
With Irfanview the un-lossy compression, 100% quality, gives a disk files size of 4350kB.

George

[George]

Just thinking.
Samples per pixel means 1 color per pixel: a raw file, not demosaiced.
Compression as how I read it means the algorithm the compression is using. For the original nef it’s Nikon Nef Compressed, for the dng it’s JPEG compressed but it is not a jpeg since it has a sample per pixel of 1.
The dng converter changes the bits per pixel from 12 to 16.
Photometric interpretation: rgb a demosaiced image, color filter array a not demosaiced image.

George