A RAW file is the image data exactly as captured on the sensor. Any settings you apply in white balance, Picture Styles and some other areas are only appended to the image as a small header file. This means they can be changed later in RAW conversion software such as Canon’s Digital Photo Professional (supplied with the camera).
A RAW file is often referred to as a ‘digital negative’ because the data can be processed and printed in different ways to produce different results – just like the negative from a film camera. Also, like a film negative, the RAW file never changes. When you open a RAW file in a software application, it is actually a copy of the data which opens. When you save this, it creates a new file on your computer. The original RAW file can then be opened again (as another copy) and worked on to produce a completely different result.
- Can be modified after capture
- Maximum flexibility
- Widest range of colours recorded
- Largest file size
- Needs computer for processing
Introduced with the EOS-1D Mark III, S-RAW provides all the advantages of a RAW file, but in a smaller file size. An S-RAW file has approximately one-fourth the pixel count and approximately half the file size of a RAW image. Just like RAW images, S-RAW images can be adjusted and processed with Digital Photo Professional software (supplied with the camera). S-RAW will appeal to wedding photographers, for example, who do not need full resolution for wedding candids, but who do need the post-production control RAW offers.
- Smaller file size than RAW (so more images can be captured to a media card)
- Lower resolution than RAW
Introduced with the EOS 7D, and also on the EOS-1D Mark IV, M-RAW provides all the advantages of a RAW file, but in a smaller file size. Depending on the camera an M-RAW file has approximately between 55-60% of the pixel count and approximately two thirds the file size of a RAW image. Like RAW images, M-RAW images can be adjusted and processed with Canon’s Digital Photo Professional software (free in the box with the camera).
Shooting M-RAW files might appeal to wedding photographers who don’t need full resolution for wedding candids, but who do want the post-production control that RAW offers. It could also be of use to sports/action photographers who will get an increase in the number of frames when shooting in bursts due to using a smaller file size. M-RAW is also worth considering if you are not planning to make prints larger than A3 size.
- Smaller file size than RAW (so more images can be captured to a media card).
- Increased burst shooting possibilities.
- Lower resolution than RAW.
A JPEG image file is a RAW file that has been converted by the in-camera DIGIC processor and saved as a compressed file. It can be saved at different image sizes and levels of compression to give different file sizes. The camera takes the RAW file and applies the camera parameter or Picture Style settings to the image to create a new file.
These settings cannot be changed once the JPEG file has been saved. It is possible to make some colour and exposure changes to a JPEG file, but you will be working at 8-bit depth rather than the 12-bit or 14-bit depth offered by EOS digital cameras.
This may not be a problem if you are making minor changes to the file and printing at sizes up to A4, but it might be significant with large changes or bigger prints. Also, a JPEG file is compressed each time it is edited and saved, and can lose some data each time.
There are two aspects to every JPEG file: Large, Medium and Small refers to the image size (the number of pixels recorded); Fine and Normal refers to the amount of compression used when saving the file. Large/Fine gives the maximum quality; Small/Normal the lowest.
- Smaller file sizes (more images can be stored on a CF or SD card)
- Images are easy to view, mail and print than RAW files
- Reduced post-processing flexibility
- Reduced colour depth and resolution
- Need to get everything correct in-camera (some computer processing is possible)