Digital Camera Image Formats: RAW Vs JPEG
This article will examine the benefits and drawbacks of shooting in RAW as well as JPEG format. (NB RAW is not actually an image format, however, we’ll get to this in the future).
The file is saved in JPEG compression format. JPEG compression format is simply that – the image stored onto the memory card has been compressed by an algorithm. Since the image is compressed there is a pervasive loss in the quality. However, the problems with JPEG are more than the image stored on the card. If you are doing any post-processing on your images each time you save a new version in the post-processing step, this compression method is applied to the picture. This can result in further degradation in image quality with each edit/save cycle. However, the typical size of a JPEG image at full resolution on a 10.1 Megapixels screen is 2.6MB.
A RAW image file only contains the information collected by the camera’s sensor. In and of itself, it’s not an image. It has to be converted prior to becoming an “image file”. RAW files are much more suitable to work with during the post-processing process. You can easily alter various aspects of the picture. The average size of an entire resolution RAW image taken with the 10.1 Megapixel camera is 9.3MB. This is about 3.5x bigger than a good standard JPEG image.
If you looked at two photos of the same scene, one in JPEG and the other in raw (without processing) it is possible that you would conclude that the JPEG image is superior and you’re not incorrect. If you take a look at a RAW image that has post-processing done, you’d believe that it’s the more appealing image. What is the reason?
One of the most crucial elements to making an image appear technically correct is getting the right white balance (I refer to it as technically since it is possible to have an image that is technically correct with poor composition, and still be a poor image). Understanding what exactly the term “white balance” means and what it does to affect an image is not the subject of this piece, however, I believe that a few sentences on the subject are necessary.
White light is comprised of all the colors of the rainbow, mixed together so that it appears like white. Some light sources (e.g. light from the sun, or an incandescent light bulb) are more prone to a higher percentage of colors that fall on the red portion of the visible spectrum, which gives the light a warmer feeling. Others types of lights (e.g. light bulbs that are fluorescent) are more likely to contain a larger proportion of the colors that are in the blue portion of the spectrum. This gives the light a “cold feeling’. To ensure that your camera is able to pick the correct colors in the scene it is “seeing it has to be aware of what proportions are present in each color creating the light. This is known as”the “color temperatures” of light. It’s determined in the form of (Kelvin).
The majority of amateur photographers use AWB (Auto White Balance). AWB is a good job of getting the color temperature (and therefore the color of the photo) right. This brings me back to my original query Why should a RAW image be superior to an image in JPEG? The answer is that RAW images are much simpler to manipulate with image editing software like Photoshop. In Photoshop you can easily alter various aspects of an image, including exposure, white balance as well as color saturation, color shade, fill light contrast, brightness, and many more. Of course, you can also achieve this using the JPEG image, however, it’s not as simple and the results aren’t as effective and we face the issue of decreasing image quality gradually due to using the JPEG compression algorithms. In Photoshop (and indeed, other image editing software) it is easy to and quickly modify a RAW image to produce a superior image over its JPEG alternative.
Now you’re probably wondering “why should you not take pictures RAW?” As we’ve discussed previously, RAW images are about 3.5x bigger than the average JPEG image. However, this is getting less of a problem since flash memory is becoming cheaper and less expensive. There’s another issue with RAW. Invoking the RAW file, editing it, and saving it to the image format (e.g. JPEG or PNG) could be slow in the case of a large number of files to deal with. There are applications that convert multiple files, however, the output isn’t as effective as individually changing and converting each individual file. There is an option to solve this. Most cameras have the ability to shoot both RAW as well as JPEG. This allows us to look over images in JPEG images and determine what ones require some tweaking without having to process and convert a multitude of RAW files.
More effective results can be achieved using RAW. But converting the images is laborious and time-consuming. It does well at rendering JPEG files on its own but it is prone to fail and it’s easier and faster to fix the error with a RAW file as opposed to one that is JPEG at the time of post-processing. If you’re using a decent size memory card, I would recommend selecting an option called the JPEG plus RAW option. When this option is selected, the camera will save both the JPEG file as well as RAW files to your memory card. This lets you quickly go at all the JPEG documents later on your computer and determine which require post-processing work which will save you lots of time when converting files. However, this will take much more memory on your card. I currently have an 8GB memory card that I believe is sufficient for a long time of shooting with a 10.1 Megapixel camera, using JPEG and RAW (my card has the following: 485 raws, and 672 JPEGs with 50MB spare).