D800 RAW vs. TIFF 16bit Question « Nikon Rumors Forum

Nikon Rumors Forum » Nikon DSLR » [D800]

D800 RAW vs. TIFF 16bit Question

(34 posts) (9 voices)

Started 6 months ago by chris_weinert
Latest reply from chris_weinert
Related Topics:

Tags:

12 Next »

chris_weinert

senior member
Joined: Oct '12
Posts: 90
offline

Hi everyone,

I have a short question: Before I got my D800, I read in some blog review about the extremely high dynamic range of the sensor, illustrated with the example of a completely under-exposed shadow area that was then pushed with the exposure slider of the RAW converter to something that looked almost normally exposed. I tried that myself, it's truly unbelievable.

Now, when you use Aperture or Lightroom or well PS to convert the RAW file into a 16-bit TIFF, is there any loss of this information of the image? Theoretically, the RAW is 14 bit, so there shouldn't, right? Meaning, if you pass it on to PS, one should be able to recover this information i.e. with a levels treatment?

Thanks,
Chris

Posted 6 months ago #
golf007sd

preferred member
Joined: Nov '10
Posts: 585
offline

To hedge against any information loss I would highly recommend making all changes to the photo and then converting it to TIFF. Though I must admit I do not work to much with TIFF files. I do 95% of my work within in LR 4 and then export to .jpeg.

Not sure if you have conducted HDR photography but that would be the best way to take full advantage of the sensor within your D800. Have a look at some of the picture I have posted on PAD via my Flickr account to see what I mean. All those shot are in combined and edit in RAW and then exported to jpeg

Posted 6 months ago #
TaoTeJared

preferred member
Joined: Apr '10
Posts: 2,422
offline

To be honest I'm not sure why anyone would choose to work in Tiff unless they have to for a client and only then as a final version. I'll convert to PSD and work in that. I do not see or know of any real advantage of Working in Tiff. It is an old file type that was used so much it still exists - other than that, I'm not sure why it is an option anymore. Files I do not edit, I leave in Nikon Raw format. Current PSD files can posses the same amount of information.

Posted 6 months ago #
chris_weinert

senior member
Joined: Oct '12
Posts: 90
offline

Thanks, golf and TTJ, for your answers!

I sort of knew in the moment I clicked "Send" that I should have not used the "TIFF" word. :-) To be precise, I am exporting to 16-bit PSD format, but then again, since TIFF is an uncompressed format it wouldn't really make a difference if I handed the file over to PS in a TIFF format and then saved the whole edited stack as a PSD.

I'm not converting any files for storage, I'm talking about the workflow for retouching.

Since I always work non-destructive in Photoshop (also the RAW conversion I make as a Smart Object), I would want to delete the 50MB-RAW files of images that I have as a PSD, though.

So the image information is not lost, that's good to know.

Posted 6 months ago #
msmoto

big gun cougar
Joined: Mar '10
Posts: 2,736
offline

@ chris_weinert....

I am totally ignorant about all this stuff, but do have some experience in goofing up and underexposing with my D4. The best example is when shooting birds against a sky and using the full screen matrix metering. This will often under expose the subject, particularly when the sun is in the photo, not directly but behind clouds.

And, I use 14 bit lossless compressed for my files, import into Lightroom 4.2. The results are quite amazing in that most of the time the dynamic range of the D4 sensor allows a decent image once corrected with the exposure and shadow sliders in LR 4.2.

I am wondering what the results of your examples are and if you could post a couple on this thread, with and without correction?

And, for my example, here is the Flickr link.

http://www.flickr.com/photos/fantinesfotos/7633984694/sizes/o/in/set-72157630700786770/

which shows the loss in the dark tonal range of the subject. This was "saved" in LR 4.2 as it was about 1.5 to 2 f/stops under by my recollection. This was at 4000 ISO BTW shot while the sun was setting in the background.

Posted 6 months ago #
chris_weinert

senior member
Joined: Oct '12
Posts: 90
offline

@msmoto: Sure, I can post the test shots, they're real test shots though, meaning ugly.

Here's just looked for the review, the one who "discovered" it was Fred Miranda here (scroll down a bit for the shadow recovery examples).

I read about this in another blog where someone was recreating this by taking a picture of his desk in an otherwise completely dark room, and then recovered the darkness. I did the same and it's true. Gonna post those later when I find the time for cropping etc.

Posted 6 months ago #
chris_weinert

senior member
Joined: Oct '12
Posts: 90
offline

Ah, just found it, it was at Luminous Landscape (scroll down to "Noise and Dynamic Range"): http://www.luminous-landscape.com/reviews/cameras/nikon_d800__e_initial_impressions.shtml

Posted 6 months ago #
msmoto

big gun cougar
Joined: Mar '10
Posts: 2,736
offline

@ chris_weinert Thank you.... what a great website..... And the shadow recovery for the D800 is certainly as good as the D4 at lower ISO. Now I suppose I have to get one of these...the D800E, instead of a D400

Posted 6 months ago #
Eric

senior member
Joined: Jun '12
Posts: 363
offline

@msmoto - Tommie, I heard a rumor that there was pool started about when you would finally get a D800E as your second body. ;) (not really)

At low ISO the shadow recovery is simply amazing.

@ chris_weinert
Although I may be wrong, it seems like converting the 14bit RAW into a 16bit TIFF may result in a loss IF you want to subsequently process the image. The RAW image uses 14bit values of red, green and blue to build up individual color pixels. As a consequence a raw image has the tonal gradient of a 42 bit color pixel. This can be mapped into a 16 bit color space and you can't see any difference. However, some post processing might result in subtle banding... This would be similar to what happens when post processing jpegs, but not as severe. Hopefully someone on PAD will know for sure.

Posted 6 months ago #
chris_weinert

senior member
Joined: Oct '12
Posts: 90
offline

Eric, thanks very much for the follow-up! What I don't understand:

Eric said:
As a consequence a raw image has the tonal gradient of a 42 bit color pixel. This can be mapped into a 16 bit color space and you can't see any difference. However, some post processing might result in subtle banding... This would be similar to what happens when post processing jpegs, but not as severe.

Ok, the 16-bit setting is per channel, resulting in 48 bits for the pixel, so the array is larger than with the original RAW. Are you suspecting that the "upscaling" or re-mapping produces artifacts, similar to... dang, what do you call that in English... you know, using levels adjustments to enhance contrast?

Posted 6 months ago #
Eric

senior member
Joined: Jun '12
Posts: 363
offline

@chris_weinert - I'm think I was mistaken. At 16 bits / channel I agree that you shouldn't lose anything. I afraid I got my image formats confused and I was thinking that it was 16 bits/pixel, perhaps an indexed color model with a look up table. So long as the RAW pixel data is combined into a similar number of RGB pixels, I don't think that the demosaicing should cause a problem. I agree with you, a 16 bit TIFF really shouldn't have any losses.

Posted 6 months ago #
chris_weinert

senior member
Joined: Oct '12
Posts: 90
offline

msmoto said:
I am wondering what the results of your examples are and if you could post a couple on this thread, with and without correction?

It's not much different from the luminous landscape stuff, but here's a shot from under my desk... Here's the original:

Here's the processed image:

And here's a crop from the marked area:

Very grainy, yes, but still impressive given the fact that it was almost completely black before adjustments.

Best,
Chris

Posted 6 months ago #
msmoto

big gun cougar
Joined: Mar '10
Posts: 2,736
offline

Yup, we could never even attempt this magic tricks with film. My D4 does the same thing. And, the noise is what is the downside. But, the effective ISO in pulling the shadows up is near 800-1600 in your shot. Actually, this is how one gets the Hi-1, 2,etc. ISO from the bodies. The camera is actually exposing with a native sensitivity and then simply lightening up the exposure, as I understand it. So with the extended ISO levels, this shadow detail tends to disappear.

Posted 6 months ago #
golf007sd

preferred member
Joined: Nov '10
Posts: 585
offline

@chris_weinert: Off Topic: That is a lot of wires...possible fire hazard if you ask me.

Posted 6 months ago #
chris_weinert

senior member
Joined: Oct '12
Posts: 90
offline

msmoto said:
My D4 does the same thing. And, the noise is what is the downside. But, the effective ISO in pulling the shadows up is near 800-1600 in your shot.

Noise is the downside? Excuse me, but this is an almost-completely black area of an exposure, it's not a "shadow" in the more classical sense. I think this is pretty much magic. I don't know what other sensors are doing, but I remember from my 5D Mark II that it was *way* different!

It actually does remind me of film: When I started developing film myself back in the analog days, I was always amazed of the incredible detail that you could get out of a seemingly completely black area that was underexposed. I can't tell whether digital sensors have gotten there yet, but I'd doubt it.

golf007sd said:
@chris_weinert: Off Topic: That is a lot of wires...possible fire hazard if you ask me.

Haha, thanks for the hint. The picture actually only shows 30% of the cable chaos, of which 80% of is audio as well as signal cables (USB, MIDI, FW etc.). What would you advise?

Best,
Chris

Posted 6 months ago #
TaoTeJared

preferred member
Joined: Apr '10
Posts: 2,422
offline

chris_weinert said:
Eric, thanks very much for the follow-up! What I don't understand:

Ok, the 16-bit setting is per channel, resulting in 48 bits for the pixel, so the array is larger than with the original RAW. Are you suspecting that the "upscaling" or re-mapping produces artifacts, similar to... dang, what do you call that in English... you know, using levels adjustments to enhance contrast?

You shouldn't see a difference but if you upscale it adds nothing at all and could introduce artifacts but unlikely. The less you change formats, color spaces, bit depth, the better in your workflow for a good result.

The only time that it could be advantages is if you create artwork with photos (vector drawings, 3d art, etc.)

Posted 6 months ago #
Gareth

preferred member
Joined: Sep '10
Posts: 591
offline

chris_weinert said:Now, when you use Aperture or Lightroom or well PS to convert the RAW file into a 16-bit TIFF, is there any loss of this information of the image?

Yes.

A RAW file is not an image. It contains more information than can be seen in one image. When you look at a RAW in LR (for example) you are looking at what the RAW would look like when the settings selected are applied and it is converted to an image (tiff, psd, jpg, etc). That is why RAW editing is non detructive. You are not editing an image, you are choosing what settings to apply to the RAW then exporting to make an image.

HDR works the same way. There is too much information in the file to be shown at one time. When you apply settings you are choosing to show some of the information and hide other information. This is called tone mapping.

When you export to the final image the information that you have chosen not to show is discarded. Only the settings you chose to keep are retained.

So if you delete those RAWs you will be throwing away information. But what's the chance that you would ever go back to an old image and rework it from scratch from the RAW?

On a side note, I often use TIF. It has many advantages. One is that you can save as lossless compressed. Another is that you can open it without Photoshop, and another is you can retain layers. I save all of my final print ready images as TIF, either to print myself, or to send elsewhere.

Posted 6 months ago #
chris_weinert

senior member
Joined: Oct '12
Posts: 90
offline

Gareth said:
A RAW file is not an image. It contains more information than can be seen in one image.

Well yeah, it is an image. It's a file that contains image data just like any other image file. There can't be more information in an image than defined by its bit depth, so it's an image file with 42 bit color depth. And of course, the full 14bit per channel can't be seen on a screen or printed out. Neither can 8bit, I'd say. But that's a different topic.

Gareth said:
So if you delete those RAWs you will be throwing away information. But what's the chance that you would ever go back to an old image and rework it from scratch from the RAW?

The chances are high that I want or need to re-edit an image that I've already retouched in Photoshop. I'm not talking about pushing some sliders, I'm talking about heavy retouching as for fashion or beauty. And of course if you re-work something, it's the best idea to have the original data and not some already processed image.

But the original point of the question was that I was wondering whether a converted image would still contain all the information of the RAW file, not theoretically (which is obvious, since 16 bit is more than 14), but practically (just to make the point, a RAW file could be downsampled to a 4-bit-per-channel JPEG quality 0.3 and then handed over to Photoshop to be converted to a 16-bit PSD).

But from everyone's comments, it looks like we all believe that everything is preserved and can hence be processed like the original RAW.

Thanks for all your input,
Chris

Posted 6 months ago #
R8R

preferred member
Joined: Aug '11
Posts: 352
offline

So just to add some confusion here - Nikon's NEF raw format is based, at least partially, on the TIFF format.

:)

A raw file contains the image data, plus a file header, EXIF, sensor metadata, a small image thumbnail, a jpeg image preview, etc etc.

All of that extra data is "tagged" with any adjustments, and is applied to the raw image data and then your viewer (LR, etc) displays the image with the adjustments applied.

Once you export to a TIF, (or any other finished file format) you are essentially making a "print" from a "negative". You are fixing the white balance settings, sharpness, contrast, highlight adjustments, shadow recovery, etc. All those sliders in LR.

You can adjust these things again with a finished file in an editing app, but you will be working on a limited range of adjustment. You might not be able to recover highlights and shadows in the same way. (if at all). Overall contrast and brightness? Yes. Recovery of an image using all that original dynamic range? Limited at best.

Posted 6 months ago #
chris_weinert

senior member
Joined: Oct '12
Posts: 90
offline

R8R, thanks for your post!

R8R said:
You might not be able to recover highlights and shadows in the same way. (if at all). Overall contrast and brightness? Yes. Recovery of an image using all that original dynamic range? Limited at best.

See, and this is what I don't understand. Why? What happens to "all that dynamic range", in other words: bits? We're talking about a 14bit/channel to 16bit/channel conversion here, with plenty of room for all that information.

Thanks,
Chris

Posted 6 months ago #
Eric

senior member
Joined: Jun '12
Posts: 363
offline

Chris. I can certainly see that if during processing you move the value any of the channels associated with a pixel up or down to clipping, then you can't recover. For example, I can easily see processing a RAW image to give me deeper blacks. If this change is saved as an instruction on top of a RAW image, then the data is still there. However if the image is flattened into a single TIFF, then the shadow data might be lost (clipped to 0). Same thing can happen when pushing saturation values for an effect. In other words, I can easily see how subsequent processing can induce clipping (high or low) into some pixels. When that happens data is lost when the image is flattened.

On the other hand, if you started with a unprocessed RAW and saved it immediately into a TIFF, then it seems to me that all that has been done is to convert the Bayer representation of the data into an RGB representation of the data. I don't think this transformation can induce clipping of the data, so it should be completely reversible and hence no data would be lost.

Posted 6 months ago #
chris_weinert

senior member
Joined: Oct '12
Posts: 90
offline

Eric, thanks for the follow-up. The part I don't understand is the clipping. Clipping occurs when the data "space", in other words the bit-depth is overdriven, meaning the data is literally clipped off. If you have a array with data in it, but export that array of data into a different format with the same dynamic range (bit-depth) without changing anything, there should be no clipping. Clipping occurs only if you either push the exposure up (and hence, values beyond the 100% value) and then save the file destructively (i.e. export the file to a different format, applying the exposure shift), or if you downsample the data into a smaller space, like convert it to a 8-bit-per-channel format. Then of course, it has to be clipped off to fit into the smaller data space, or it could be compressed into the 8-bit space, but then you lose the tonal differentiation, because between 0 and 1 you now only have 256 steps instead of 16384 (14-bit RAW).

Clipping is the stuff that you can see in a histogram when you push the exposure and values get pushed beyond "full white" for example. But if you simply do nothing to the 14-bit depth data and just port it to another format, the dynamic range is still 14 bits, or well even 16. So no clipping, nothing cut off, nothing lost.

Or where is my mistake in the logic?

Posted 6 months ago #
Eric

senior member
Joined: Jun '12
Posts: 363
offline

Chris, no mistake. My last post agrees with you. What I meant to convey is that if any processing is done prior to the conversion to TIFF, then as R8R indicated the conversion can irreversibly lock the associated changes into the image. If those processing steps resulted in any clipping, then data ends up being lost.

The RAW file always has the initial image data at maximum fidelity. A TIFF file might have some losses (depending on any processing done to the RAW before conversion to TIFF). Any losses are a consequence of processing done pre-conversion.

I agree that you should be able to take the camera RAW data into a TIFF without any losses. In fact I think you could take such TIFF data and extract the original RAW data.

As I see it, losses can only arise when the RAW file is processed and subsequently converted to a TIFF. In the most minimal case this can be integer round off and in more severe cases channel clipping (which ends up shifting colors). Since virtually any processing will likely result in integer rounding, then a subsequent conversion to TIFF will have some, perhaps imperceptible, loss.

Posted 6 months ago #
TaoTeJared

preferred member
Joined: Apr '10
Posts: 2,422
offline

Tiff files do not retain the raw data. It is no different than making a print from a negative, and re-scanning it, then editing it.

Case in point - when you convert a NEF file, the white balance (and other settings) are set and applied. Therefor it changes the original tone of the file which can limit your ability to process it. If you WB Bracket a set of sunsets, the colors will swing across the spectrum. RAW files, you can change those back to Neutral (remove the WB) - Tiff files you can not do this.

Tiffs are best as a the "final" print/save in a workflow - not at the beginning of it.

Posted 6 months ago #
Ironheart

senior member
Joined: Sep '12
Posts: 91
offline

Last I checked a TIFF file is larger than the corresponding RAW so there is no advantage especially when you consider the non-destructive editing you get by default with RAW. For example, As TTJ pointed out WB adjustments are easily changed or backed out from RAW but after conversion would be difficult. Also noise reduction algorithms seem to work better on RAW files.

But don't take anyone's word for it. Try it out for yourself. Try noise reduction per and post conversion and be your own judge. Same for the WB. If all you are worried about is pulling data out of shadows, then the 16 bit TIFF conversion should preserve most of it. But try it and let us know.

Posted 6 months ago #