Basic Photo Theory and Digital Workflow (2 of 4)



RAW or Jpeg?


There is one more decision to make before we go any further... and it's a biggie! Do you want the photographs you shoot saved as RAW files or Jpeg files? The choice will have a significant effect on the quality of your images, their overall suitability for some uses, and the post-processing workflow required to get the most out of them.

We all know Jpeg images. They are the standard image file format used today. Anything from web graphics to sending photos as email attachments will use the Jpeg (.jpg) format. The reason for its popularity as a format is that it is a variable compressable file. That is to say, when we save our image as a Jpeg we can choose how much compression on the image file to use. This has two effects. Depending on the compression factor, the actual file size can vary considerably, making it a great tool to reduce file size when sending email attachments etc. The down side of this is, the more compression you add, the worse the resolution of the image becomes, with visual 'artefacts' becoming quite noticeable at high compression rates.

Original Image
High Compression Jpeg
This is not an issue if all you want is the ability to send small snaps to friends, but can become an issue if you are trying to get the highest resolution from your digital SLR camera. That's not to say that very reasonable images can be provided from your camera in Jpeg mode, but you should ensure that no compression is used. Some cameras also save images in a Tiff file format, which is a better format again. On the plus side, you will get more images on your memory card, and images taken on your camera in Jpeg format can be loaded directly into your graphics software with little or no post-processing for immediate use. Most cameras in Jpeg (or Tiff) mode will allow basic processing such as sharpness, contrast, saturation etc. to take place in camera, and can therefore produce images in an almost 'ready to print' state.


However, if you are wanting the very best quality images from your camera, you should really be shooting in 'RAW mode'. This saves your images as raw digital data, directly from your camera's sensor. It doesn't pass through any software filters or have any in camera settings applied. This is your image in its purest form, at the highest resolution your camera can provide.

The down side of shooting in RAW is that file sizes can be huge, depending on your camera's sensor resolution. Although most cameras allow the user to swap between Raw + Jpeg/Tiff mode, saving 'mixed' file types onto your memory card. Also, before you can use the RAW image, it has to be converted from its raw data state to a more conventional graphics file format (such as Tiff or Jpeg), but before that, you have to tweak the image, adding sharpening, colour, contrast and other exposure tweaks. This is known as post-processing. Although this looks like a lot of work to get your image into a useable state, the beauty of working in Raw is that you have a lot of control over the exposure of your image AFTER it has been taken, as you're effectively still adjusting the digital 'code' of the image. It is only when you save your processed image in another file format that the exposure of the image is 'locked', so to speak.

For this reason, most keen photographers will always shoot in RAW, and their workflow will include using a RAW conversion program (preferrably your camera's own branded software) for initial tweaks to sharpness and exposure. They will maintain their original RAW file as their digital negative (don't overwrite it with a tweaked version), and will use the saved Tiff or Jpeg file as their working copy of the image to be finalised in Photoshop, Paint Shop Pro or another graphics application.

For my own digital workflow, I 'usually' save a copy of my RAW file as a backup digital negative, preferrably on a separate drive. I work on the original RAW file in my RAW conversion software and save out as a Tiff file (without compression), which then becomes my working file for output or further work in my graphics application (in my case Paint Shop Pro). The finished image is either re-saved as a Tiff file for hir-res output or as a Jpeg for lo-res output.




Theory & Workflow continued (3 of 4)...