What am I doing wrong?

[DanK]

That's the entire point. There is no reason not to view the histogram, but when you do it must be viewed in the context of the scene being photographed.

I'm not sure I agree. Optimizing the histogram optimizes the quality of the capture. Tonality can be changed in post.

This is a big issue in night photography, which I do a bit. Most often, one wants the final image to be quite dark. However, if the histogram doesn't span the entire range (often the case for outdoors night photos, as opposed to urban ones with bright lights), one can get a better image by ETTR and then darkening in post.

[Manfred M]

I am having trouble coming to grips with what people are saying here. Firstly, I don't see that the image as first presented is simply under-exposed. I took the image and increased the exposure in photoshop and the brightest parts of the petals quickly became blown out. The problem to me is the flatness of the tones. When I changed the "gamma", things improved and the image changed along the lines of Nandakumar's version, which was a great improvement.

Also, with respect to what Dan said, shooting a little on the dark side is often a good thing, particularly if there is a high dynamic range in the scene, provided circumstance allow you to do so with the ISO low. Th exposure can then be corrected in pp. It is true that that will give a worse signal to noise ratio but if the ISO is low that should not be too much of a problem, less of a problem than dealing with important areas that are blown out.

With reference to Manfred's comments, if you take a picture of a snowscape with automatic exposure, it will come out grey. But when you look at the histogram, it will be dead centre, which might look correct. While the histogram gives much information, it still needs to be interpreted in the context of the picture.

Perhaps I now need to duck for cover.

Tony - the reason we view the image as underexposed is that the histogram shows blocked shadow details. i.e. the histogram has a lot of information on the left side, yet the image really does not have a lot of data on the right hand side, yet the flower is quite light. A number of Brian's recent postings show this characteristic. On has to read the histogram in context, i.e. look at the scene.

With respect to the camera's metering of snow coming out gray and being "dead centre", well, sort of. If you take a picture of just a black card, white card and gray card in auto exposure will look identical; a single line in the middle of the histogram. If you are discussing using a SOOC image, this is an issue, but if you are planning to correct things in post, I would give a different answer. When I shoot, I try to get a good distribution on the histogram and given the choice of biasing to the left or right, I would compensate to the right (ETTR). If you handle in post, then getting good material to work with is going to be different than shooting for SOOC.

Low ISO is going to help in reducing noise, but I can certainly show you properly exposed low ISO images that have a lot of noise in the dark areas. If we are looking at relatively small areas, it might not be too bad, but if we are looking at the night sky, the noise will not be a good thing.

[xpatUSA]

I am having trouble coming to grips with what people are saying here. Firstly, I don't see that the image as first presented is simply under-exposed. I took the image and increased the exposure in photoshop and the brightest parts of the petals quickly became blown out. The problem to me is the flatness of the tones. When I changed the "gamma", things improved and the image changed along the lines of Nandakumar's version, which was a great improvement.

Also, with respect to what Dan said, shooting a little on the dark side is often a good thing, particularly if there is a high dynamic range in the scene, provided circumstance allow you to do so with the ISO low. Th exposure can then be corrected in pp. It is true that that will give a worse signal to noise ratio but if the ISO is low that should not be too much of a problem, less of a problem than dealing with important areas that are blown out.

Perhaps I now need to duck for cover.

Absolutely not, I agree fully with the sentiment of your post.

Inspired by your post, I took another look at the original posted image using 'Show Image'. I looked at the 'Lightness' and 'Saturation' maps in the HSL space.

The Lightness histogram (which is similar to Luminosity) showed a slight Lightness under-exposure - but that is due to there being next to no green in the rose petals. Like you yourself said, increasing the exposure in RawTherapee quickly starts blowing the red channel in the brighter parts of the petals.

The Saturation histogram was another thing entirely! The whole petal area had quite low saturation, around 25%, which seemed on the low side to me even for a pink rose.

So I went to RawTherapee and played with the basic sliders:

Lightness: 0 (no change)
Contrast: +16 (made it less "flat")
Saturation: +19 (took the petals up to about 45%)

Some reds did get blown but only in the petals' specular highlights.

I moved the shadows up a bit:

Blacks: -6718 (big number but fairly small effect, negative means "less black").

Also sharpened a bit but the rose looks just as nice slightly soft, IMHO.

Et Voila!



Realizing that Brian has already expressed dissatisfaction with his original PP, this post is still about how to fix the originally posted image but, hopefully for Brian, it may have some relevance to Brian's original processing itself.