Black Point / White Point.

[joebranko]

Thanks John. I use Lightroom for my processing.

[joebranko]

Thanks Chauncey

[joebranko]

Joe - . I leave the clipping indicators turned on for the histogram and press the <alt> key when I set the black and white points. .

Thanks Manfred. This is the way you showed me several month ago, and this is how I set them now. What I don't know is, at what point do I adjust black/white points? And do the adjustments to WB, Tone presence etc affect black/white point?

[joebranko]

Yes, sometimes you do work back and forth a bit, but not much.

Thanks Judith. This has been my experience when I go back to it. Wasn't sure it was the correct procedure.

[Manfred M]

Ted what is actually happening is that we are resetting the values of anything to the left of the black point to pure black and and anything to the right of the white point to pure white and then redistributing all of the other colour values to give a full tonal range to the image. So you are not really increasing contrast, but you are opening up the image and making it more colourful / vibrant.

[Manfred M]

Thanks Manfred. This is the way you showed me several month ago, and this is how I set them now. What I don't know is, at what point do I adjust black/white points? And do the adjustments to WB, Tone presence etc affect black/white point?

Joe - look at post #25, it explains what is happening. It will not impact WB at all.

[joebranko]

Thanks Urban.

[joebranko]

Thanks Brian

[joebranko]

When setting the White and Black points, I also leave a bit of space either side of the histogram in ACR for the stretch that later application of Local Contrast Enhancement (LCE) via UnSharp Mask (USM) will cause. (i.e. the lowish amount/large radius USM)

.

Thanks Dave. Not sure Lightroom supports this process. I have to spend some more time in the sharpening process it does provide.

[xpatUSA]

Ted what is actually happening is that we are resetting the values of anything to the left of the black point to pure black and and anything to the right of the white point to pure white and then redistributing all of the other colour values to give a full tonal range to the image.

Of course.

So you are not really increasing contrast, but you are opening up the image and making it more colourful / vibrant.

Doesn't sound right, Manfred.

In the image below, I did the recommended Levels adjustment. The global contrast was increased by the adjustment.



In HSB space the grayscale % brightnesses were as follows:

dark, mid, light
Before 21, 31, 57
After 16, 34, 84.

dark/light contrast (H-L)/(H+L)

Before: 0.46
After: 0.68

Am I missing something?

[Manfred M]

Am I missing something?

Probably me not explaining things well enough. Let me think about it and get back if I can figure out a better way of explaining it.

Contrast is increasing values of the lighter tones and decreasing the values of the darker tones (applying an "S" curve to the histogram). That is definitely not what is happening with the black point and white point adjustment.

[xpatUSA]

Probably me not explaining things well enough. Let me think about it and get back if I can figure out a better way of explaining it.

OK

Contrast is increasing values of the lighter tones and decreasing the values of the darker tones (applying an "S" curve to the histogram).

Herein appears to lie the difference, maybe.

What that is, is one method of the application of contrast, rather than the value of the contrast once applied. As we know, contrast can be applied by several means; not just curves and not just levels. For example, wavelets. Another example, unsharp masking.

That is definitely not what is happening with the black point and white point adjustment.

Since I just showed clearly that it is what is happening, I await your proof to the contrary . . .

[Manfred M]

I think the use of the word "contrast" is the issue. It covers too many things. Unsharp mask, for instance does effect edge contrast, which is local contrast, but that is not the same a the global contrast of an image.

Re-reading your post, I do agree with you. Adjusting the black point and white point the way I describe does increase the global contrast of the image, it has to.

[Shanghai Steve]

This is an interesting thread. Good to see how others work.
My own workflow is not nearly so complex. If I mess up the exposure, I bin the shot. However, since I rarely shoot skies or landscapes at all, this makes life a lot easier for me than for some. I do remember being extremely unhappy with almost every landscape shot I have ever taken- they just never seem to have that pop that I see from many photographers. I spent 24 hours travelling to Huanshan, spent a day on the mountain and I look at what I took on this majestic mountain and think "Is that it?" But for my normal shots, I work thusly:
Convert RAW shots to Tiff in Sony's Image Data Convertor
Work on Gimp 2 to...
Straighten
Crop
Decide whether the image looks better in mono or colour
Adjust white balance if needed
Adjust levels, often pulling shadows down.
Sharpen
Noise reduction
Export as JPG.
I don't do layers or anything like that, though I don't discount this in the future.

[xpatUSA]

This is an interesting thread. Good to see how others work.
My own workflow is not nearly so complex. If I mess up the exposure, I bin the shot. However, since I rarely shoot skies or landscapes at all, this makes life a lot easier for me than for some. <>

But for my normal shots, I work thusly:
Convert RAW shots to Tiff in Sony's Image Data Convertor
Work on Gimp 2 to...
Straighten
Crop
Decide whether the image looks better in mono or colour
Adjust white balance if needed
Adjust levels, often pulling shadows down.
Sharpen
Noise reduction
Export as JPG.
I don't do layers or anything like that , though I don't discount this in the future.

Take one Brownie Point for an Adobe-free workflow

Anarchy rules!

[JBW]

This is an interesting thread. Good to see how others work.
My own workflow is not nearly so complex. If I mess up the exposure, I bin the shot. However, since I rarely shoot skies or landscapes at all, this makes life a lot easier for me than for some. I do remember being extremely unhappy with almost every landscape shot I have ever taken- they just never seem to have that pop that I see from many photographers. I spent 24 hours travelling to Huanshan, spent a day on the mountain and I look at what I took on this majestic mountain and think "Is that it?" But for my normal shots, I work thusly:
Convert RAW shots to Tiff in Sony's Image Data Convertor
Work on Gimp 2 to...
Straighten
Crop
Decide whether the image looks better in mono or colour
Adjust white balance if needed
Adjust levels, often pulling shadows down.
Sharpen
Noise reduction
Export as JPG.
I don't do layers or anything like that, though I don't discount this in the future.

Shanghai, seeing as you are using Sony to convert why not try Capture 1 Sony Express for converting and doing so of the work you now do in GIMP. Capture 1 and Sony combined to put this together. It works well and it truly is free.
https://www.phaseone.com/en/Products...y-Express.aspx

[joebranko]

So to summarize, good photographic practice is to NOT clip at either the dark or light end during capture, but it is GOOD practice to slightly blow out to pure black and pure white in the final image to create a good colour range.

Thanks again Manfred. I read somewhere not in this site, that it is recommended to expose 'to the right' to ensure that you capture all the details in the highlights. This I take it is not recommended?

[joebranko]

Thanks Ted.

[Manfred M]

Thanks again Manfred. I read somewhere not in this site, that it is recommended to expose 'to the right' to ensure that you capture all the details in the highlights. This I take it is not recommended?

It is still recommended, but if you look at when that concept came out, 2003, I think, the sensor technology was still pretty primitive and it was much more important. The theory behind it is still quite sound.

The same goes for HDRI, it came out at a time were the dynamic range of sensors was much lower than they are today, so it was needed when you had a 15 or 16 stop dynamic range. Today, I can get better results by manually blending one or two images.

[Shanghai Steve]

Shanghai, seeing as you are using Sony to convert why not try Capture 1 Sony Express for converting and doing so of the work you now do in GIMP. Capture 1 and Sony combined to put this together. It works well and it truly is free.
https://www.phaseone.com/en/Products...y-Express.aspx

That's Great!
I'm on that site now.
Cheers.