Raw Converter Review

What is Camera RAW?

When you press the shutter button on your digital camera, the image is exposed on a chip in your digital camera called a sensor.  Color is typically captured on your sensor in 12 bits of color per color channel.  All of this information is captured into an area of working memory in a format typically called camera RAW.  From this buffer it is saved onto your memory card in the format you have selected in your menu system.

All cameras capture the image in a RAW format, but not all cameras give you the ability to save your image to your card in that format.  Some point and shoot cameras give you a mode to save your images in RAW and most digital SLR cameras give you the option to save in RAW format.  You typically have several image sizes in your menu to choose from, small, medium, large and each size comes with a level of fineness (normal or fine) that sets the compression algorithm that the JPEG compressor will use to save the image to your memory card.  If you have a RAW setting in this menu then your camera will let you save your images as RAW files.

When your camera converts the RAW image data to JPEG, it reduces the color depth from 12 bits to 8 bits of data, so you immediately lose dynamic range of your color. Images with 12 bits of color depth hold 16 times the amount of information that an 8 bit color image has. You lose information in the highlights and shadows that you can never recover.  Much of this discarded information is not even noticeable by the human eye, but it’s there, and if you keep it you can use it later to bring out the details in those highlights and shadows.

Lossless vs. Lossy

JPEG also compresses the image data to make the file smaller and part of it’s compression algorithm involves throwing away significant amounts of data.  This is called “lossy compression”.  You can see why JPEG files are smaller, they are throwing away picture information that your camera doesn’t think you need.  Also, when your images are converted to JPEG, certain decisions are made during the compression process regarding camera settings such as white balance and your “creative zones” settings, that affect every pixel.

RAW images are compressed and stored in a lossless format, so all of the image data is preserved.  This can make the file HUGE.  RAW files also save all of the EXIF data, so it records all of your significant camera settings that can be used to help render your image in your raw converter program. 

Why Pros Shoot RAW

Professionals shoot almost exclusively in RAW mode.  Why?  Because professional photographers want to have as much artistic control over the final result as possible. Why let your camera make your artistic choices for you?  Cameras manufacturers are doing a better and better job of producing stunning JPEG images, but if you want to get the most out of your camera, you should consider shooting in RAW.

Disadvantages of Shooting RAW

RAW files can be big.  Big image files means less images on your memory card, and more space used up on your hard drive.  It also means longer file transfer times from your camera to your computer and more data to backup (you are backing up your pictures, right?  If not, try Mozy, up to 2 Gigabytes for free!)

Photolabs, photo printers, and slideshow programs do not know what to do with RAW files, so you have to convert your images to JPEG to share them.  This means more steps in your workflow.  Special programs called RAW converters are required to convert your RAW files into into widely distributed JPEG files.  But the right RAW converter program is where you unlock the artistic potential of your photography.

In my next post I will review several RAW converter programs.

Dean Johnson