Histogram

To increase my familiarity with the histogram in both my camera and editing software I took a series of photographs. The photographs were split in to three types; low contrast, high contrast and average contrast. Of each type I would then take three different exposures (one f-stop apart) making nine photographs in the series in all. I was to take note of the histogram in my camera at the time of shooting and then compare it with the histogram in the editing software (in this case Aperture). I should state now that I would expect to find find the histograms in both camera and software very similar, especially if both are calibrated correctly. I will elaborate further after logging this piece if I find that isn’t he case. I also expected before I shot that it would be difficult to take a ‘flat’ (low contrast) image due to the dynamic nature of the light here in Singapore.
The results and explanations are displayed below. The screen grabs show the histogram and highlight and shadow clipping warning information.
Please click on the images to enlarge them.

Low contrast – f/5.6

Screen grab of f/5.6

Low contrast – f/6.3

Screen grab of f/6.3

Low contrast – f/7.1

Screen grab of f/7.1

This shot was taken in natural light but hidden away from direct sunlight. Due to the lack of dynamic light affecting the image, the histogram is bunched in to the middle and there are no clipping warnings present. There is really not much change in shape between the histograms. The histograms relate directly to what I saw on my camera’s LCD screen when taking them. There is also not much change in image between f-stops although the shot taken at f/7.1 is possibly a little darker as you would expect.

High contrast – f/13

Screen grab of f/13

High contrast – f/14

Screen grab of f/14

High contrast – f/16

Screen grab of f/16

This shot through the trees in to a rising sun gives a high dynamic range. This shot is showing the camera failing to cope with the extreme highlights and extreme shadows. It can be clearly seen in both the histogram (peaking on both the right and the left) and also the clipping warnings (blue and red). Although difficult to see, the red warnings are occurring on the water as red spots on the very extreme highlights. This is interesting, as on my camera, I could clearly see than there were clipped highlights occurring by looking at the histogram. However, I could not see them on the clipping warnings (which I had turned on in camera) as they were too small to see on the LCD. So it makes me realise I have to pay attention to both systems of warnings (whether I choose to heed them or not is a different matter). The screen grabs show that the camera is struggling to capture the shadowed areas more than the highlighted areas. As I close the aperture down the shadows start to recede until at f/16 the shadow on the wall starts to gain detail. The highlighted areas remain about the same throughout the exposure changes.

Average contrast – f/9

Screen grab of f/9

Average contrast – f/10

Screen grab of f/10

Average contrast – f/11

Screen grab for f/11

So, this is the set that confused me slightly. Not because of the highlights on the white surfaces of the buildings, I would certainly expect that in bright sunlight. What confused me is the correlation between the histogram and the clipping warnings of these areas. On the histogram both in camera and in the software I would expect to see a ‘spike’ on the right-hand side telling me that my exposure was over and yet there is none. The histogram gives quite a broad range of exposures.

After having had a quick sit back and think about this I have realised that the lack of spike (and by spike I mean that I would expect to see the left or right peaking off the top of the histogram) is relative to the overall image contrast. As there is a not as broad a range of contrast as in the previous set (High Contrast) the peaking is all relative and can still be seen on the right hand side as a sharp peak. On left-hand side of the histogram the black area is quite rounded as the dark areas are fairly close together in dynamic range. So, in conclusion, the histogram is just not acting as I would have previously expected, which means yet another thing to look out for when shooting! I have left the first paragraph in here to show my thinking process.

As a footnote I found that the histograms between camera and Aperture compared favourably. This, of course, is great as it gives me confidence that I what I shoot will be translated in to what I am editing.

The bright sunlight in Singapore and throughout the tropics gives rise to some beautiful photographic opportunities.  The dynamic nature of the light is what gives the stunning contrasty images that are so good to take and great to look at. On the flip side, it can be very difficult to control and for every shot you get right there are many, many others that are not right. As I suspected, trying to take a flat shot in daylight was not very easy without hiding from the sun. My main opportunity for taking a flat/low contrast shot would be just before or after rain or during the ‘haze’ when the the clouds or smoke diffuse the light dramatically. Even then it is still remarkably bright. Fortunately I don’t have too much desire to take low contrast shots unless I’m asked to in an exercise for college!

A very interesting exercise which much food for thought.

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