Friday, July 27, 2012
Basic Photo Terminology, Part 1
JPEG Straight From Camera
Fully Tweaked RAW Version-1
This is the first of a two part Post in which I will explain some of the basic Photo Terminology, sometimes called "Parameters" or "Styles" that you might run across. Part-1 will deal with the more basic set of terms which are probably adjustable for the JPEG output within the Picture Menu of your camera - in other words, you can use nothing but the "Picture Styles" (or some other such term, depending on your camera model) to adjust these Parameters. The approach I'll use here is to show you what can happen when some of these Parameters go wrong, and what you must do to correct them. I will be using the picture above throughout this exercise. For starters, the first one - the JPEG output from my camera with the Picture Style set to "Faithful" is sort of OK - I had exposed to get the most detail from the clouds, but overall, the picture is a little bit ho-hum, especially in the foreground. The second sample is the same picture, but I worked a lot on the RAW file to give it some added punch. For new photographers, I want to take this opportunity to mention that this shows the power of shooting RAW files - I could never have accomplished this degree of enhancement by trying to tweak a JPEG file.
But on to the Terminology. The first one is -
Positive (High) Exposure
I don't want to say this is "over-exposed" especially, because you can see that the foreground is correctly exposed, and if this is what you wanted to accomplish, then this is the correct exposure. However, you can see that the best part of the picture, in this case the spectacular clouds, is all blown out, because the exposure was set higher than in the original JPEG.
Solution- in Photoshop (or equivalent), reduce the Exposure by one or two points. Next -
Here you can see how a bit of Contrast Boost has an overall benefit to the picture in this case - compared with the Camera JPEG, an increase in the contrast really enhanced the detail in the clouds, as well as added some much needed brightness to the foreground. This is the way Contrast works - it is very linear, in that it will boost both the highlights and the deeper shades at the same time. But quite often, you might not want to boost both the shadow and highlights at the same time. It worked well in this picture, but it's quite rare that Contrast Boost alone will have such a good overall effect.
Solution - set your Camera's Contrast setting 1 or 2 points higher, if you want overall good contrast. Next-
The Saturation Adjustment only works on the colour levels of the picture, and not on the Tonality. Here the top picture shows reduced saturation - as you can see, it's almost Black and White. In fact the most common way of converting colour to B&W is simply reducing the Saturation all the way to Zero (although common, this is not necessarily the best way). In the bottom picture, I increased the Saturation quite a bit, making all of the colour in the picture really "pop", but not really adding anything in terms of detail, especially in the foreground. If the foreground looks a little brighter, it is only because the colours are more intense.
Solution - if you want bright cheerful colour, increase the Saturation setting in your Camera. Next-
Gamma Adjustment Badly Needed
This can be a tricky one. At first glance, pictures with Gamma problems look over-exposed, but the problem doesn't go away by using an Exposure adjustment. Instead, it's like a bright milky film or glaze is all over the picture, and it's usually caused by too much UV light coming in. The use of a screw on UV Filter on you lens usually prevents this from happening, but if you don't have one, all is not lost. Gamma can be taken out by adjusting it with software. Depending on the software you use, it is sometimes accomplished differently - sometimes you have to move the Gamma slider to the + side and sometimes to the - side. Some other software's use the terms "Blackpoint" and "Whitepoint", where you have to work with both sliders, either + or - to eliminate the haze.
Solution - there is no "in camera" Gamma adjustment, at least not with Canon products, but you can use most anyJPEG editing software to get rid of the haziness. Next, the last one for today -
Sharpness is another Parameter that can be set via your Camera menu in most models. It is exactly as the name suggests - how sharp or "un-blurry" a picture can be. Naturally a lot of this depends on the lens you are using, how good you are at focusing, and the lens aperture setting, but there is also a Sharpness component within the pixels of the photo itself. I demonstrated it here by cranking up the sharpness to the extreme limit, and you can see both the positive and negative effects of doing so. It made the picture quality very snappy overall, but it also created some obvious problems in the "Irving Circle-K" signs. There are photo styles, especially Portraits, where you should reduce Sharpness, which is usually more flattering to the subject.
Solution - Sharpness is best set in your camera itself, based on what you want to achieve. Choice of lens is also important here. Software adjustment of sharpness after the photo is taken is effective, but is done "artificially" which will be obvious if you are too heavy-handed with it.
Part 2 of this tutorial will deal with Parameters that can only be done outside the camera, by processing your RAW files. I broke it up this way because not everybody has a camera that will output a RAW file.