A few weeks back I wrote a post about RAW and JPEG. In it, I told a little story about baking a cake and I let on the fact that I was a complete chocoholic. Well, for those that found that post interesting, this may tick a few boxes too.

A couple of days ago, one of the blog readers, Steve, dropped me an email with two small histograms attached. They were from the same image but one was the RAW version of the file and the other was the JPEG. Now at first thought, you may expect the histograms to look the same. But they don't. Similar yes, but the differences are obvious - and they show the advantage of a RAW file over a JPEG. 

 On the left is the histogram from the JPEG file, on the right is the histogram from the RAW file. Can you spot the difference? 

Well, it's quite obvious if you look at the edge of the trace lines - the RAW file histogram has a smoother outline with fewer sharp peaks and troughs. The question is... why? 

Well, it's quite simple really, and it's to do with bit depth. Bit depth defines how many different, or unique, colours an image can contain. A JPEG file can only be 8bit wherease a RAW file from the camera used to produce this image (an EOS-1D Mark III) is 14bit. While 8bit provides 16.7million unique colours, 14bit provides 4.3trillion unique colours.

It's this extra colour data and the corresponding smoother tonal gradation between each tone that makes the histogram smoother. 

Does this mean that RAW is better? Well, if you're planning on trying to really maximise the ability of your camera to capture data so you can have the most data to work with afterwards, then yes, RAW is better. However, you need to ask the question of whether you will notice the difference in the final image. In many cases, it's unlikely you would, but you can never tell beforehand what the final use of an image will be so my view is to capture as much as possible and throw data away rather than capture less and be unable to create it. 

As an addition to this, people often ask about printing and the fact that surely you need an 8bit file. Well, that used to be the case, but modern printers are so good now, especially the Canon PIXMA range, that they can deal with, and make use of, a 16bit file. This means prints look better, colours are more accurate and there is less chance of tonal stepping where gaps emerge between discrete colours because of extreme image processing. 

One of the great ironies of the last couple of years (from a Canon EOS photographic point of view rather than a global perspective) is the introduction of Picture Styles (PS). Before PS we had parameters, and they caused a lot of confusion. While we could sort of understand what contrast, saturation, sharpness and colour tone did, no-one ever seemed to do anything with them. So Canon came up with the idea of packaging them as Picture Styles, with some simple names to make them easy to understand. And yet we still have confusion... and people not changing them! 

So, here's a run-down of the 6 preset Picture Styles and what they are used for. They are split into three groups - Basic, Advanced and Monochrome.

Basic - for general shooting, these are aimed at users who either don't want to post-process their images, or who don't want to have to do too much work to their images. Basic includes Standard, Portrait and Landscape. Each setting offers a different level of sharpening, but it the other parameters (see that word creep back in?!) all seem to be 0, and yet if you take the same picture with the three different settings, they'll look different becasue of the tone curve applied to the image in settings you can't control.

Advanced - for those that want to post process their images and would like the images to be as untouched as possible from the camera. It includes Neutral and Faithful. Neutral gives natural colours and gentle tones without boosting the contrast or sharpness. Faithful adjusts the colours based on a 5200K colour temperature to try and match the colours accurately. Again there is no contrast or sharpening applied.

Monochrome - for black and white shooting. There is also the option to add toning or filter effects at the point of shooting. 

So what should you use? Well, if you use Canon's DPP software, you can change the  Picture Styles in the post processing as you wish. you can even create your own Picture Stlye in Picture Style Editor and apply that to your image to create a repeatable custom look. If you use a third party RAW software then with the exception of the latest versions of LightRoom/Adobe Camera RAW, Picture Styles will be completely ignored and it will be effectively the equivalent of shooting in Neutral - i.e. flatter tones, neutral colours and no real punch. 

So what about sharpening? Well, the thoughts on sharpening are that it is now a three stage process - capture sharpening, creative sharpening (optional) and output sharpening.  If you use one of the Standard PS settings that applies sharpening, this is effectively stage one done. If not, you'll need to do it in processing - this means also if you use third party RAW software that ignores PS settings you'll miss out on the first stage.

If you want to see what Picture Styles look like on an image, here's a comparison set with nothing done except to change the Picture Style on each one, and a resize to fit the page. 

Standard:

Landscape:

Portrait:

Neutral:

Faithful:

Mono: