Is converting to DGN/tiff lossless

yndesai

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I was looking at converting my .arw file to .dgn/.tiff so that it can be processed in older version of software.
Just wondering if this conversion will be lossless would use Rawtherapee for this purpose.
 
It is NOT lossless. All raw formats capture FAR more data than you need to make a photo. Conversion to tif or any other bit mapped format throws away all the data NOT needed to make a photo that looks like you want it to look. That is why you REALLY need to save your raw files if you even suspect you might need to revisit the discarded data.
 
I would be keeping the raw file as a backup. But since I have latest camera and older software I was wondering howmuch would I lose in case I process tiff or convert to dgn.
 
You would have to be a pixel peeper of huge proportions for your eye to notice the difference.

Claude
I agree.

Still can you tell few things which I should adjust before converting to dgn / tiff. Also I understand DGN is also more like raw file format which keeps lot of data.
 
DGN is the Bentley Systems CAD format for Microstation, widely used in manufacturing, utilities mapping and construction design. I assume you did not mean that.

If you mean re-saving of camera raw to DNG (not DGN), the original sensor data is unmodified when you do this; it is just being enclosed inside a different file format.

The DNG includes enough of the metadata from the starting file, to allow the Raw data to be decoded into an image.

The only difficulty is that when software is interpreting a Raw image by means of its generic DNG support, and does not yet support the camera-original Raw format directly; it is not yet equipped with any camera model specific calibration, may not do lens corrections, may not understand special exposure modifying features such as Active D-Lighting, etc.

In other words, it will work for now, but it will work better when the software is upgraded with support for that camera, at which point the DNG conversion is no longer necessary.

Conversion to TIFF always throws away a certain amount of adjustability. This is more than a re-packaging, it is complete re-representation of raw data into a bitmap. It also throws away the possibility of making better or simply different raw conversions for that photo in the future - because your requirements change, your skills and judgement improve, you get a better monitor or a better calibrated one, or your software improves (or you use different software).

RP
 
I was looking at converting my .arw file to .dgn/.tiff so that it can be processed in older version of software.
Just wondering if this conversion will be lossless would use Rawtherapee for this purpose
Assuming you mean DNG that would be the better choice. A TIFF is very large and not a RAW file format. DNG is a RAW file format and you retain all the original pixel data quality. That said, there may be options available when you save as a DNG. Photoshop Elements has one option called "Embed Fast Load Data". If you check that, then there is a JPEG like compression applied, and associated loss in quality. The file size is dramatically lower. If your interest is in ultimate quality you should not use that option or anything similar that RawTherapee may have.
 
If you are talking about DNG, then Adobe claims that it is lossless. Of course, there is always an exception. The DNG converter available from Adobe has an option to create "lossy" DNG files. They are intentionally compressed and you have to consciously choose to do that. I have used the DNG format in the past. I have never been able to detect any loss of quality. It is supposed to reduce the size of your raw files (the DNG file contains the original raw image data). But on my Nikon camera there is only about and 8% savings. There is nothing wrong with the DNG format. I just choose not to use it.
 
But it is impossible for conversion from ANY raw format to tif to be lossless. That act of conversion is, by its very nature, deciding what stuff you want to throw away.
 
So if I correctly understand the answers here, conversion form RAW to TIFF always involves a loss of quality.

Therefore, IIRC (it's been awhile since I tried PS), since you convert from RAW to TIFF to work in Photoshop, working in PS always results in a loss of quality. Interesting.
 
When I go to Photoshop I always save a 16 bit tiff image. If there is quality loss I haven't been able to see it. I always save TIF images with no compression. There are those who will say that TIF images with compression are lossless. I have no data to confirm or deny that.
 
When I go to Photoshop I always save a 16 bit tiff image. If there is quality loss I haven't been able to see it. I always save TIF images with no compression. There are those who will say that TIF images with compression are lossless. I have no data to confirm or deny that.
This is a VERY simplified explanation. I'm sure much more detail could be added to it, but I think it is adequate for a high level explanation.

The image you see on the screen in your raw editor already is a bit mapped conversion. your program displays the the image according to the default values your raw editor has built into it. The extra information is there in the raw file, but not displayed on screen. If the conversion no longer needs certain data to meet your needs, it is deleted from the on-screen representation, but not from the raw file itself.

As you make changes, your raw editor goes into the raw file and displays any additional information it needs to create the image as you want to see it. But at no time does the image you see on screen represent the ENTIRE set of data contained in the raw file. I suspect we would not recognize it as an image at all if it did.

As an ex DBA, I tend to think of raw images as a sort of mini database for the creation of a single image; not as the image itself. As you work with the image you read that database looking for the information you need to create the image.

Once you have altered the on-screen representation to your satisfaction, and you tell it to export or save to a tif file, what gets converted to tif is that onscreen representation. And this leaves behind any unused data in the raw file when the tif is created. And you would not see any loss in a good conversion compared to the onscreen representation.

This is why I claim that any conversion from raw to tiff is inherently 'lossy'. The Raw development process is one of deciding WHAT raw data to use and what to leave behind. It is also why you always want to save your raw images if you can. You never know when an alternate development and conversion will be useful.
 
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So if I correctly understand the answers here, conversion form RAW to TIFF always involves a loss of quality.

Therefore, IIRC (it's been awhile since I tried PS), since you convert from RAW to TIFF to work in Photoshop, working in PS always results in a loss of quality. Interesting.
I would suggest a conversion to TIFF means more of a loss in ability to further adjust the image, but not a significant loss in quality as it is. In other words if you make all your adjustments in Adobe Camera RAW, or Lr, then convert to TIFF you are not likely to see any loss in quality of that image. Theoretically yes, but for all practical purposes no. To preserve ability to make further adjustments, especially if you are going to use another RAW developer, it would be better to use a DNG format.
 
So if I correctly understand the answers here, conversion form RAW to TIFF always involves a loss of quality.

Therefore, IIRC (it's been awhile since I tried PS), since you convert from RAW to TIFF to work in Photoshop, working in PS always results in a loss of quality. Interesting.
I would suggest a conversion to TIFF means more of a loss in ability to further adjust the image, but not a significant loss in quality as it is. In other words if you make all your adjustments in Adobe Camera RAW, or Lr, then convert to TIFF you are not likely to see any loss in quality of that image. Theoretically yes, but for all practical purposes no. To preserve ability to make further adjustments, especially if you are going to use another RAW developer, it would be better to use a DNG format.
It is better to stay in a nondestructive RAW based flow as long as you can, but my experience is that 16bit TIFF files take adjustments as well as RAW files, to the degree that I can detect with my own eyes. Which can't be said for JPEG files.
--
- Bill
 
When I initially bought my Nikon D7000, my first DSLR, I wanted to know more about the digital world. So I bought a copy of Peter Krogh's book — The D.A.M. Book (for digital asset management).

It is a little outdated today, but Krogh essential wrote the bible on digital photo formats. One of the big issues he addressed is the fact that various mediums become obsolete. Remember 8-Track car stereos from the late 1960s? Or Sony Beta TV recording equipment?

He said that new technologies render the storage of data obsolete with alarming regularity. He bemoaned the fact that digital camera manufacturers can't settle on a sort of 'Rosetta Stone' format that would be interchangeable between camera brands and PP software.

At the time, he thought that Adobe's introduction of the DNG protocol would be the 'lingua Franca' of everything related to DSLR. And thus readable by all cameras and all PP software.

Unfortunately, like any business, Adobe turned out to be somewhat protective and guarded in their business plan and so DNG wasn't universally accepted by makers of hardware and software. You can't really blame Adobe.They are in business to make a profit.

But I say, hell with DNG and insist on maintaining my entire photo library in the Nikon RAW format. Also known as NEF. Most files are close to 30Mb each. :-(
 
Unfortunately, like any business, Adobe turned out to be somewhat protective and guarded in their business plan and so DNG wasn't universally accepted by makers of hardware and software. You can't really blame Adobe.They are in business to make a profit.
To be fair, most camera manufacturers have actively chosen to use (and promote) their own proprietary Raw formats, rather than DNG, and not because Adobe have put them off in some way - quite the reverse, AFAICT. Pentax for one example, have offered DNG as an alternative to PEF for several years, without apparent difficulty.

But it is in Nikon, Canon etc's interest to lock users into specific software which supports brand-specific proprietary functions. Probably, Pentax were not in the commercial position of dominance where that was any possibility, so sought to realise a different unique-selling-point.

And in fact that has paid off: new Pentax cameras are already supported by those means (in a generic manner) long before the software update which explicitly supports them, and even long before the release of the relevant DNG converter from Adobe too.

If (for example) Nikon can persuade a camera owner to commit to a NEF-specific workflow - it raises the difficulty bar for switching brand. So Nikon will seek to promote the supposedly unique, claimed advantages of that, and even to encrypt or protect it to the extent they can commercially get away with. It is not in Nikon's (and most other manufacturers') interest to cooperate fully on the basis - which Adobe CAN seek to propose, lacking any skin in the game - that camera raw formats should be treatable as in effect, non-proprietary and interchangeable.

RP
 
A raw file has a bit depth of either 12 or 14 bits. That represents 4,096 or 16,384 levels of tonal values depending on the bit depth of the raw file. How does converting either to a 16-bit file (65,536 levels or tonal values) result in loss; or stated another way why would such a conversion be characterized as lossy?
 
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I understand that Leica cameras can actually be set to save to the SD card in DNG format. Wow. German engineering. Very forward thinking.
 
However while the tiff file contains and image made by post processing your cameras RAW pixel data. The tiff file contains no raw data. That data remains in your DNG file which only has a scaled down preview jpeg rgb image in some color space. The actual pixel raw data is not a RGB color image in any color space. The actual pixel data must be processed into a color Image in some color space and color bit level to be useful. The conversion is not save as a RAW file its saved in some image file format tiff is ofter used for it can be layered and many programs support Tiff files. However Browsers do not Tiff files.
 
If you are talking about DNG, then Adobe claims that it is lossless. Of course, there is always an exception. The DNG converter available from Adobe has an option to create "lossy" DNG files. They are intentionally compressed and you have to consciously choose to do that.
Beware the difference between lossless conversion and lossless compression. I expect DNG to have lossless compression. And one would hope that any converter would do lossless conversion (as far as possible).
 

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