How far to the right are you?

[george013]

Your seem to be confusing 2 different things Geogre, dynamic range differences between raw and visual images/jpg's and dynamic range in a raw file against transfer characteristics used in cameras and PP packages to generate a visual image.

If a subject uses up all of the dynamic range available in the raw file it could be mapped as described directly to a jpg but it wouldn't look very good. If the dynamic range in the subject just falls short of generating blinkies or even well short the mappings that are used will give a decent image directly in an ideal world. I'm not mentioning problems around the blinky point at the dark end. Separate aspect.

In some ways there is little point in the post that shows different ;levels of clipping. For one is it a channel, all channels, 2 channels or what? The main reasons for the difference are what happens to the raw data which is loosely speaking as follows

Raw file -> Camera Colour Profile -> Colour Temperature Correction -> Mapping to the visual image / jpg etc

If Nikon camera and Adobe are compared only the raw file and colour temperature correction are the same with some doubts about the latter being exactly the same. Actually it's the same with Canon as well and probably all cameras as Adobe do what they feel suits the camera. The manufacturers do their own thing. Packages do their own thing too which is why they produce different initial results but in principle all could be used to generate an image which to all visual aspects are identical. Start measuring pixel values and there are likely to be differences as each package is very likely to use different methods of getting there.

If you find a package changes the image when you EXPORT to jpg and reload something is decidedly wrong. The whole point of a PP package is to actually show what you will get when the image is viewed on anything in principle but monitor calibration or lack of it etc can mean that different people will see different things. A common reason for apparent changes in brightness in images is the colour of the background also the work that some one has just done on an image. That tends to concentrate peoples attention to what ever they are adjusting - not the entire image.

John
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John,
I'm getting tired of this. There is no way you seem to understand what I'm writing. Nowhere there is been talking of the dynamic range. Just comparing the same visual image: one RAW via the converter and one JPG. Just as simple as that.

Think about what you're saying here and what I'm trying to show you. And what you can find out yourself. I tell you a little secret: the difference is called JPG-COMPRESSION. Don't tell further.

If you find a package changes the image when you EXPORT to jpg and reload something is decidedly wrong.

Beside that, one of the differences between converters is the used white balance. Even the colour temperature for daylight sunny is different between camera brands and converters. Nikon has the name to be some cold, to blue. So also different blinkies on the end.

George

[xpatUSA]

Ted,
With all respect, again you don't see the issue. It's about the statement that there seem to be more info in a RAW-file than in a JPG and in-camera blinking happens earlier in a JPG then in a RAW.

OK, to help me see the issue, can you be more precise about this "info" and these "blinkies":

Firstly, to save me searching back through this thread what is meant by "info"? Secondly, are the blinky settings exactly equivalent when viewing the file in raw and in JPEG and what are those settings actually in your system?

Like you, I would never expect blinkies to be the "same" between a raw rendered image (rendered meaning presented on your screen) and the same image converted to JPEG and rendered on your screen. My reasons are probably different to yours:

1) To show proper color, the image must be converted from camera raw space to an RGB space. Each channel is scaled up or down (a gross over-simplification) to make the colors look right to the eye. That means that blinkies will be different.

2) Next, the JPEG must be saved with sRGB or Adobe (1998) profiles (others are also possible). These profiles can affect blinky levels in the JPEG but not, of course, the source raw file.

We can not state that blinkies will occur earlier or later. That depends the camera, the converter and all the settings used, in-camera and out. To make a point, my camera will often show over-exposure in the on-camera 3-color histogram when there is no clipping in the raw data. This is commonly called "head room" - but I can not tell everybody that this happens on all cameras as a statement by itself with no qualification. Thus it is that your personal test mentioned below for the information of others does not prove a general rule for everybody.

If a RAW-converter works standard with a 16-bit workfile doesn't add anything to that. The camera gives a file with a bit-depth of 10,12,14 or whatever your camera is set on.

This statement is too general. My camera for example stores a 16 bit per channel raw file and the data values in it can go to double or three times the 12-bit ADC max output of 4095, due to in-camera raw processing before writing to the card. Few cameras are as simple as we might think!

And a JPG is 8-[bits per channel], without decimals.

Yes, I think we all know that, George, so what was meant by it?

[Choose] a RAW-picture with blinkies light and dark, load it in the converter and write it back to file as a JPG. Then open it again and compare the two files and [their] blinkies.

George

In your opinion would it be at least as valid, if not more informative, to compare the histograms?

[ajohnw]

You have to go to some lengths to see raw blinkies in camera George so what on earth are you comparing. Actually as it's been tried it's doubtful that it's even possible to make a camera show true raw blinkies - unless at some point they add it.

The reason for this is dynamic range - the 2 are different raw to jpg. Some with a 14bit d/a say I have a 14 stop range, some say displays have 8 or even 7. neither is really correct for several reasons. Prints - some might reckon 4.

John
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[Stagecoach]

So in essence it all comes down to what YOU see on YOUR cameras Blinkies and how that compares with the Blinkies indicated when YOU open YOUR files in the software YOU use.

What you will NEVER know is how the manufacturer of YOUR camera has designed HIS software to show Blinkies derived from the image taken and shown on YOUR 3" LCD.

[ajohnw]

That's it in a nut shell plus there is no saying what curve the camera has used or the software has used to convert raw to what ever image type it happens to be.

The only things that is fairly certain is that the basic raw file is the same but that might get converted to prophoto, melisa or even perhaps uncle fred or even 8 bit and heaven know what that might do before anything gets colour managed or not to the screen.

John
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[chauncey]

So in essence it all comes down to what YOU see on YOUR cameras Blinkies and how that compares with the Blinkies indicated when YOU open YOUR files in the software YOU use

Like I said...it's all minutia, it matters not a whit.

[xpatUSA]

Like I said...it's all minutia, it matters not a whit.

Attention to minutiae, both in theory and in practice, is one means of improving one's photographic performance. Ignoring it and saying that "it matters not a whit" is not.

[Stagecoach]

Attention to minutiae, both in theory and in practice, is one means of improving one's photographic performance. Ignoring it and saying that "it matters not a whit" is not.

Rather a 'generalised' statement Ted.

Based upon what one considers performance with respect to photography, the ability to produce images for which you and others go WOW or the ability to quote scientific information.

The art comes in recognising which minutia is best suited or applicable to improving the individuals photographic goals

[ajohnw]

It does matter in some ways WM but no so much if some one has a distorted view of what goes on. Not a brilliant example but .......

Shot at this exposure on purpose, colours all wrong as a result




Easily converted to colours about as accurate as the camera is capable of without calibrating it.



The sort of thing I amuse myself with at times.

John
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[Stagecoach]

Shot at this exposure on purpose, colours all wrong as a result

Easily converted to colours about as accurate as the camera is capable of without calibrating it.

The sort of thing I amuse myself with at times.

John
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Interesting John, but why is it that if you crop a section out of the original flower, paste it into the modified version the colours are the same as I can see?

"All wrong", mmmmmmmmmm

[xpatUSA]

Interesting John, but why is it that if you crop a section out of the original flower, paste it into the modified version the colours are the same as I can see?

"All wrong", mmmmmmmmmm

Indeed, the pixel at 507, 231 is 335.2 degs hue in the one shot and 334.5 degs hue in the other. Quite a difference in the Lab Lightness though.

As our President Bill might have said: "it all depends on what the meaning of 'colours' is . . "

[Stagecoach]

Indeed, the pixel at 507, 231 is 335.2 degs hue in the one shot and 334.5 degs hue in the other. Quite a difference in the Lab Lightness though.

As our President Bill might have said: "it all depends on what the meaning of 'colours' is . . "

Ted, whilst I would not dispute the difference at pixel levels as it's measured for the position you have quoted and the brightness what I find more interesting is the difference in appearance when blown up to full size.

It appears to me that the 'difference' between adjacent pixels is far more prominent in the original as if the modified image has been smoothed (or whatever) in some way. Not a function of contrast/brightness as far as I can see but would be interested to know the reason.

[ajohnw]

Ted, whilst I would not dispute the difference at pixel levels as it's measured for the position you have quoted and the brightness what I find more interesting is the difference in appearance when blown up to full size.

It appears to me that the 'difference' between adjacent pixels is far more prominent in the original as if the modified image has been smoothed (or whatever) in some way. Not a function of contrast/brightness as far as I can see but would be interested to know the reason.

I see a distinct colour difference Grahame, basically lighter in the 2nd one - just what I intended, on the other hand I might just have posted the image I used to produce the 2nd one but don't think so.

Try this one but where the black background version is pass



It was a bit late at night here.

John
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[george013]

John,
I don't know what you try to show or proof. If the original is the one with a black background and the second is where the blacks are edited/lifted, then I don't see a correlation with the title of this thread, the discussion on highlight blinkies or your statement of extra space you have in raw-clipping.

George

[xpatUSA]

Ted, whilst I would not dispute the difference at pixel levels as it's measured for the position you have quoted and the brightness what I find more interesting is the difference in appearance when blown up to full size.

It appears to me that the 'difference' between adjacent pixels is far more prominent in the original as if the modified image has been smoothed (or whatever) in some way. Not a function of contrast/brightness as far as I can see but would be interested to know the reason.

Well, I got ImageJ reloaded successfully, so had a look at histograms of part of a petal, both in RGB and in the Red channel, voila:





TBH, all I see is a difference in luminosity, see min, max and mean. Very little difference in contrast, see StdDev. If the "the 'difference' between adjacent pixels" (micro-contrast?) were markedly different, I would expect significantly different standard deviations and/or histogram spreads.

Comments from your goodself and John are invited . .

[ajohnw]

Silly of me not to post the correct ones, other than the one that was very likely to be the actual exposure, I would have to wade though originals to be 100% sure but chances of it not being are remote.

I'm inclined to feel it's better to under expose in some circumstances - as some one else mentioned and for the same reasons. Pity it doesn't work the other way round so well with say a black coloured bird but I will persist with trying to use the same basic idea at that end too but adjustment wont be so easy. Dam monitors I suspect.

John
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PS what package is that Ted?
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[JHzlwd]

A deliberately provocative title to get your attention. I just read a very interesting Luminous Landscape article yesterday that I see Allan referenced in this thread without sparking any discussion.

IMO this discussion just goes to demonstrate my contention that the camera recommended exposure settings are just that ... recommendations likely to prove reasonable when you are in too much of a hurry to do some of your own work. I regularly swing right or left, sometimes by as much as two stops. Spot-read a white coated hare and your intuition should inform you the subject will come out gray with everything else underexposed.

I find nothing very profound in the referenced article but as an exploration of the importance of intelligent exposure control it's very good and a useful reminder to engage our brains when machines provide advice.

Best wishes,
g.