Ok thanks for that she will take it back to the tutor but like said it probably not worth just for pic manipulation on the course
What it could be, is that if the course is actually teaching picture manipulation, that the computers they are using for the manipulation are not powerful enough to properly handle RAW images in a timely fashion.
There is never any point in throwing away data if you don't need to. So, if you have a system that is capable of displaying RAW, and manipulating it, you might as well use it.
However, if by using RAW you are adding 20 seconds to a manipulation (as you will be using a 16 bit image, rather than 8 bit image [although I believe that Canon and Nikon use 14 bit at the most, the closest 'standard' is 16 bit] you will be doubling the bits in use), then if it is to just demonstrate an idea, a jpeg will do.
Someone posted a link to this site the other day:
http://ronbigelow.com/articles/articles.htm
This uses 8 bit JPGs to demonstrate the effects, but it is clear enough as to what the effects are.
If the output of the class is to learn the techniques of producing a masterpiece, rather than necessarily to produce a masterpiece, then jpg will do.
This thing about saving the images.
JPG uses a loss-full compression. So every time you save a /change/ to an image, you might compress the image and loose a little bit of the data. So a line might become slightly blurred. If, you open the image, change one pixel, then save it, at the same compression level as before, you may not necessarily loose any real data. It depends on how the data is being compressed.
There is no reason, why you cannot open a JPG, and then save it as a TIFF. This uses a compression (if selected) which is loss-less. So for example, a ZIP file is loss-less. What you put in can always be retrieved.
Or save it as a PSD file, if you are using Photoshop.
But then, if you are going to be saving as a PSD or Tiff, it really makes no sense why there was a warning-off of using RAW.
I suspect it was because they have had issues with some makes of camera's RAW files not being openable by the machines involved.
RAW also blurs the boundary a bit on image manipulation. In that, by default the RAW data is manipulated by a set of 'rules' before opening it properly. So for example, the contrast is defined as you open it. The starting place for brightness is defined etc.
This might I guess be confusing for some people.
