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P: Output Linear Tiffs

Participant ,
Oct 19, 2021 Oct 19, 2021

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It would be great if one could output raw linear tiffs from a raw file. That is a file with no adjustments in exposure or curves but can utilize the lens profiles. Anyone think of a way to bypass the auto-correction to exposure in ACR?

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16 Comments
LEGEND ,
Oct 20, 2021 Oct 20, 2021

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You've been able to do that since about day one; outuput to a linear color space. 

You simply need a linear output profile which is easy to actually make in Photoshop (Color Settings). 

 

You cannot, with any raw converter produce a TIFF (rendering) with NO adjustments. 

And nothing in ACR/LR has any effect on exposure. That only takes place when you press the shutter. You can of course adjust brightness of the final rendering, from data that really looks like this:

raw

Author “Color Management for Photographers" & "Photoshop CC Color Management/pluralsight"

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Participant ,
Oct 21, 2021 Oct 21, 2021

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We have been using MakeTiff app from ColorPerfect for years to make raw TIFF files, that is no exposure adjustment or curves but outputing the raw sensor response. They look like your example above, very dark. Is that what you say is possible with ACR? Attached jpg is what MakeTiff tiffs from a raw NEF file look like. _DSC5928.jpg

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LEGEND ,
Oct 21, 2021 Oct 21, 2021

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Linear data can look “dark” because of a lack of a ICC profile and being incorrectly previewed with the wrong profile for that data. There is nothing inherently “dark” or otherwise per se with linear rendered data.

Author “Color Management for Photographers" & "Photoshop CC Color Management/pluralsight"

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Participant ,
Oct 21, 2021 Oct 21, 2021

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Not sure of what you are inferring from the supplied jpg. It has an embedded profile, in this case AdobeRGB. Since it is raw output it would not really matter what profile is or is not embedded. If there is not an embedded profile PS would display using the Colorspace default. Is it possible you are confusing linear output with raw sensor output? Whatever, I stray from the original inquiry. That is, is it possible to get a file like I have posted from ACR?

You say that it is possible. I believe you. Just how would one accomplish that?

 

You noted above that you can do that with Color Settings in PS. How would one do that exactly? Thanks for the info.

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LEGEND ,
Oct 21, 2021 Oct 21, 2021

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quoteNot sure of what you are inferring from the supplied jpg. It has an embedded profile, in this case AdobeRGB. 


Exactly, and that is the WRONG profile if indeed this is a linear TIFF! Adobe RGB (1998) has a gamma curve and it looks wrong because you are handling it wrong. This is basic color management (or a basic color management failure to preview image data).

There is no 'default' color space in Photoshop, there is a color space (RGB Working Space) that you select. IF the image has no embedded ICC profile, that is the assumption. Something always has to be assumed here. In your case, you're embedding the wrong profile, another incorrect assumption and the data previews dark and incorrectly. If you assigned a linear gamma profile to a gamma corrected image, the opposite would be seen and again, that preview is simply wrong. 

I'm not confusing anything, kind of the opposite <g>. 

You first need to understand what you actually want here. Again, rendering INTO a linear color space from raw has been an option in ACR for decades! Do you have a linear RGB Working Space you want to render into? If not, do you need to learn how to make one (then use it)? 

Start with  the concepts of linearity and gamma:

http://digitaldog.net/files/LinearityandGamma.pdf

Next, read about what scene referred rendering from raw is, is this what you want? 
http://www.color.org/ICC_white_paper_20_Digital_photography_color_management_basics.pdf

If so, your next stop is here:

http://www.color.org/scene-referred.xalter

But nothing you've asked for, that IS possible from a rendered raw isn't possible in ACR; for decades. 

Author “Color Management for Photographers" & "Photoshop CC Color Management/pluralsight"

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Participant ,
Oct 21, 2021 Oct 21, 2021

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Andrew:

 

Excellent info. Read your Linearity and Gamma article many years ago. Very good.

 

However i never said I wanted the resulting file to "look" correct. I was remiss in saying I wanted a linear output. I want a raw tiff that looks like the example I uploaded. It is a downsized version of a raw file converted by MakeTiff to a tif. Yes, it is extremely dark. I do not know how it is rendered by that software, thus my initial question.  The question....How to accomplish the same result with ACR? Is it possible?

 

You said... But nothing you've asked for, that IS possible from a rendered raw isn't possible in ACR; for decades. 

Not sure what you mean here, sorry.

 

Thank you for taking the time to explain all these concepts.

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LEGEND ,
Oct 21, 2021 Oct 21, 2021

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Why would you want an incorrect preview? Embed a profile that defines the data. Which will happen if you render from ACR using a linear profile that correctly defines this data. 

What I mean again is what you are asking for is both possible with ACR and has been for decades and outlined in the URLs provided. 

Author “Color Management for Photographers" & "Photoshop CC Color Management/pluralsight"

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Participant ,
Oct 21, 2021 Oct 21, 2021

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Why would I want an incorrect preview? The answer is that the file will be used in another software that only wants to see that "dark" file, whatever that is technically. The software uses that file data to apply color correction and color management. It is call ColorPony by ColorYoke.

 

It applies a color characterization of the specific camera's sensor, measured spectral data or pallettes of measured data, a white card exposure covering the entire scene and spectral data of the white card. The white card exposure allows the use of an internal Robin Myers Equalight-type software of luminosity balancing across the entire field of view. The resulting tif file's color rendering is very close to the original.

We have been using this software for year to create very good giclee prints for our artists and clients.

I was hoping to use ACR to apply lens profiles to reduce chromatic abberation. Using the Nikon 105 micro and Tamron 90mm macro although very good still exhibit some aberration.

 

 

I think we will continue our current process and abandon any efforts to utilize ACR to prep our our raw files.

 

Thanks for all the info.

 

Cheers,  Barry

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LEGEND ,
Oct 21, 2021 Oct 21, 2021

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You didn't answer why you want a lie of a preview by using the wrong profile and subsequent conversation. The data is the data either way. 

Anyway, what you asked for (output raw linear tiffs from a raw file.) is entirely possible from Adobe raw converter. 

Author “Color Management for Photographers" & "Photoshop CC Color Management/pluralsight"

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Participant ,
Oct 21, 2021 Oct 21, 2021

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That's right. In this case the data is the data. The preview is irrelevant to the purpose of the file. It is merely a step in a process not an end use file. I seem to be unable to convey the process clearly as you want to know why I want a file that is very dark. It is the process, it works and is used by quite a few imaging professionals like me.

 

I have explained about the linear tiff not really being what I am looking for. Correct? I need a raw tiff, like the example I uploaded. Any profile embedded does not affect the calculations in the process I use. Gamma corrrection is not needed. Just the data, RGB numbers. This process does not lend itself to raw file conversion in the standard sense as we normally approach it. We usually want a representation of the properly exposed scene. I properly expose the file according to normal procedure but I do not want that "correct" looking file for the reason above.

 

If there is a way to create that kind of file in ACR, please let us know how to do it.

 

Thanks for all the help.

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LEGEND ,
Oct 21, 2021 Oct 21, 2021

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quote

I seem to be unable to convey the process clearly as you want to know why I want a file that is very dark.

It isn't (necessary) very dark! If you really want a dark image, under expose it. Or dial down your display to as low is it can go and wear sun glasses <g>. It appears 'dark' because it isn't previewing correctly by your own doing. If you insist in viewing a linear image, with a gamma correction, which is not recommended nor useful, nor truthful, by all means do so. Or crank down the "Exposure" slider in ACR and (actually) affect the brightness WITH proper color management (and you'll get RGB numbers that are not bright enough). I can't fathom why anyone would want that, but that's how you get that ugly, dark image. 

You as yet, haven't explained what you want other than in the first post, I've quoted it and again, you can get that easily and could for decades. 

IF you actually want a representation of the properly exposed scene, you need RawDigger. And then perhaps, render scene referred as outlined in the ICC white paper I co-authored and which clearly shows a 'dark' and unattractive image in that sta te. Without it, or access to an actual raw Histogram, I have no idea how you know anything about the exposure of this raw data. 

Once you clearly tell us what you want, other than a linear TIFF (easy), someone, perhaps other than I can answer the question. You've been directed to instructions to produce scene referred TIFFs from ACR. 

Author “Color Management for Photographers" & "Photoshop CC Color Management/pluralsight"

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Participant ,
Oct 22, 2021 Oct 22, 2021

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A direct quote from ColorPony manual follows.
Copyright ColorYoke

 

Begin quote:

 


3.3. Converting RAW images
Instructions for converting camera native RAW images to a TIF format compatible with ColorPony.
Step 1

If your camera’s native RAW file format is not TIF, follow the instructions below to convert the RAW images to a TIF format compatible with ColorPony.
1. Run CAM2TIF converter 2. Click Add Images to add one or
multiple images to be converted
• When adding an image, you can add one image at a time or you can use the <CTRL> key to select more than one image.
3. Click Convert it! to begin the file conversion
•  Successfully converted files will have the same name but a TIF extension. These TIF files can be loaded as either Artwork Images or White Images into ColorPony. 

•  The converted images can be loaded into other programs like Adobe Photoshop but they may look incorrect because they are still in the RAW format of the camera. 


 

Using CAM2TIFF, (not supported for new cameras, replaced by MakeTiff app by Colorperfect) raw files are converted to tiff. As you can see it says the files will not appear normal.

 

When the shots are taken they are exposed as a normal shot.
The shots look normal on the preview on the back of the dslr. The exposure is refined by looking at the RGB numbers for white card exposure. RGB at near 230, 230, 230.

When we use the Betterlight Scanback we shoot and expose using a repro tone curve and custom ICC profile to make sure the exposure is correct. We turn off all color management and curves in the file download giving a raw sensor tiff. Very dark.

ColorPony does the raw conversion from either the converted NEF/Tiff or Betterlight raw Tiff using it’s own software.

 

So, all I am inquiring about is how to replicate the RAW file conversion that CAM2TIF or MakeTiff using Adobe Camera Raw instead. It may not be possible with the existing software architecture in ACR. I know it is quite an arcane process and seems convoluted but it works.

 

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LEGEND ,
Oct 22, 2021 Oct 22, 2021

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quote

When the shots are taken they are exposed as a normal shot.

The shots look normal on the preview on the back of the dslr. The exposure is refined by looking at the RGB numbers for white card exposure. RGB at near 230, 230, 230.

 

There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.” -Søren Kierkegaard

 

Exposure takes place in only one situation; when you click the shutter, never afterwards. 

Exposure is based on two and only two attributes: shutter and Aperture; the control over how much light strikes the sensor. Not ISO, not anything after the shutter is clicked. 

The shots on the back of the LCD are based on the JPEG. This isn't raw exposure, it has nothing to do with raw exposure, it tells you nothing factual about the raw exposure! A raw Histogram does, so get a copy of RawDigger. 

Before we go any further, you need to accept what exposure is, where it takes place and how it is based on the data you intend to capture (raw vs. JPEG which differ). 

Articles on exposing for raw:
http://www.onezone.photos
http://schewephoto.com/ETTR/
https://luminous-landscape.com/the-optimum-digital-exposure/
http://digitaldog.net/files/ExposeForRaw.pdf
https://www.fastrawviewer.com/blog/mystic-exposure-triangle
https://www.fastrawviewer.com/blog/red_flowers_photography_to-see-the-real-picture
https://www.rawdigger.com/howtouse/exposure-for-raw-or-for-jpegs
https://www.rawdigger.com/howtouse/beware-histogram
https://www.rawdigger.com/howtouse/calibrate-exposure-meter-to-improve-dynamic-range

 

ACR/LR, in fact NO raw converter has any role on exposure; proper for that data or otherwise. 

Again, for hopefully the last time, san's exposure: ACR and LR can render data into a linear color space. Both have been able to do this from the day they were released. 

Author “Color Management for Photographers" & "Photoshop CC Color Management/pluralsight"

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LEGEND ,
Oct 22, 2021 Oct 22, 2021

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quote

If your camera’s native RAW file format is not TIF,

 

Nearly all raws, and those from a Betterlight (I first shot one in 1999, with the aid of Mike Collette for this:http://digitaldog.net/files/Filmvsdigital.pdf) are based on TIFF. 

 

https://en.wikipedia.org/wiki/Raw_image_format

Many raw file formats, including IIQ (Phase One), 3FR (Hasselblad), DCR, K25, KDC (Kodak), CRW CR2 CR3 (Canon), ERF (Epson), MEF (Mamiya), MOS (Leaf), NEF NRW (Nikon), ORF (Olympus), PEF (Pentax), RW2 (Panasonic) and ARW, SRF, SR2 (Sony), are based on the TIFF file format.[3] These files may deviate from the TIFF standard in a number of ways, including the use of a non-standard file header, the inclusion of additional image tags and the encryption of some of the tagged data.

 

quoteThe converted images can be loaded into other programs like Adobe Photoshop but they may look incorrect because they are still in the RAW format of the camera. 


 

This is equally incorrect. A raw cannot be 'opened' in Photoshop, but raws can be opened in ACR and rendered so they can be opened in Photoshop. 

 

Whoever these ColorYoke folks are, they need their users to use more critical thinking about what they tell them. 

I'll forgo the comment about how raw sensor data isn't an acronym <g>. 

 

 

Author “Color Management for Photographers" & "Photoshop CC Color Management/pluralsight"

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Participant ,
Oct 22, 2021 Oct 22, 2021

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I have explained to the nth degree how I am shooting. After 40 years as a professional photographer I think I have figured out exposure. Let's just move on.

End of thread.

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LEGEND ,
Oct 22, 2021 Oct 22, 2021

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LATEST

And I've been a professional photographer as long (look it up: https://www.linkedin.com/in/digitaldog/).

And when moving from film to digital, I had to actually learn the massive difference between exposing for JPEGs and raw data, hence all the URLs you are welcome to ingore. The text you posted from ColorYoke about exposure etc, is simply incorrect.   

You asked for something that exists in the product. Enough said. And yes, this is the end of the thread and conversation. 

Author “Color Management for Photographers" & "Photoshop CC Color Management/pluralsight"

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