Home > Learn About Photography > RAW, JPEG and TIFF RAW, JPEG and TIFF by , 2004 (updated June 2008) There seems to be a lot of confusion among some new digital camera owners about exactly what the difference is between RAW, JPEG and TIFF files. article is intended to be a very basic guide to these file types and how they are related in a typical digital camera. The digital sensor in the majority of digital cameras is what is known as aThis relates to the arrangement of red, green and blueA typical sensor looks like this: Each pixel in the sensor responds to either red, green or blue light and there are 2 green sensitive pixels for each red and blue pixel. There are more green pixels because the eye is more sensitive to green, so the green channel is theThe sensor measures the intensity of light falling on it. green pixels measure the green light, the red the red and the blue the blue. readout form the sensor is of the form color:intensity for each individual pixel,

where color can be red, green or blue and intensity runs from 0 to 4095 (for a A conventional digital image has pixels which can be red, green, blue of any one of millions of other colors, so to generate such an image from the data output by the sensor, a significant amount of signal processing is required. processing is called Bayer interpolation because it must interpolate (i.e. calculate) what the color of each pixel should be. The color and intensity of each pixel is calculated based on the relative strengths of the red, green and blue channel data from all the neighboring pixels. Each pixel in the converted image now has three parameters: red:intensity, blue:intensity andIn the end the calculated image looks something like this: RAW data (which Nikon call NEF data) is the output from each of the original red, green and blue sensitive pixels of the image sensor, after being read out of the array by the array electronics and passing through an analog to digital

The readout electronics collect and amplify the sensor data and it's at this point that "ISO" (relative sensor speed) is set. Cat Adoption Milton FlIf readout is done withMagnetic Curtain Rod Walmart Canada little amplification, that corresponds to a low ISO (say ISO 100), while if theHuskita Puppies For Sale In Pa data is read out with a lot of amplification, that corresponds to a high ISO setting (say ISO 3200). As far as I know, RAW isn't an acronym, it doesn't stand for anything, it just means raw, unprocessed, data. Now one of two things can be done with the RAW data. It can be stored on the memory card, or it can be further processed to yield a JPEG image. below shows the processes involved:

If the data is stored as a JPEG file, it goes through the Bayer interpolation, is modified by in camera set parameters such as white balance, saturation, sharpness, contrast etc, is subject to JPEG compression and then stored. advantage of saving JPEG data is that the file size is smaller and the file can be directly read by many programs or even sent directly to a printer. disadvantage is that there is a quality loss, the amount of loss depending on how much compression is used. The more compression, the smaller the file but the lower the image quality. Lightly compressed JPEG files can save a significant amount of space and lose very little quality. For more on JPEG compression see If you save the RAW data, you can then convert it to a viewable JPEG or TIFF file at a later time on a PC. The process is shown in the diagram below: You'll see this is pretty similar to the first diagram, except now you're doing all the processing on a PC rather than in the camera.

Since it's on a PC you can now pick whatever white balance, contrast, saturation, sharpness etc. youSo here's the first advantage of saving RAW data. You can change many of the shooting parameters AFTER exposure. You can't change the exposure (obviously) and you can't change the ISO, but you can change many other parameters. A second advantage of shooting a RAW file is that you can also perform the conversion to an 8-bit or 16-bit TIFF file. TIFF files are larger than JPEG files, but they retain the full quality of the image. They can be compressed or uncompressed, but the compression scheme is lossless, meaning that although the file gets a little smaller, no information is lost. This is a tricky concept for some people, but here's a simple example of lossless compression. Is there a way to store this that doesn't lose any digits, but takes lessThe answer is yes. One way would be as follows Here the string 33333 has been replaced by 3[5] - meaning a string of 5 3s,

and the string 888888 has been replaced by 8[6] - meaning a string of 6 8s. You've stored the same exact data, but the "compressed" version takes up lessThis is similar (but not identical) to the way lossless TIFF compression I said above that the data could be stored as an 8 or 16-bit TIFF file. data from most high end digital camera contains 12 bit data, which means that there can be 4096 different intensity levels for each pixel. In an 8-bit file (such as a JPEG), each pixel can have one of 256 different intensity levels. Actually 256 levels is enough, and all printing is done at the 8 bit level, so you might ask what the point is of having 12 bit data. The answer is that it allows you to perform a greater range of manipulation to the image withoutYou can adjust curves and levels to a greater extent, then convert back to 8-bit data for printing. If you want to access all 12 bits of the original RAW file, you can convert to a 16-bit TIFF file.

Why not a 12-bit TIFFBecause there's no such thing! Actually what you do is put the 12 bit data in a 16 bit container. It's a bit like putting a quart of liquid in a gallon jug, you get to keep all the liquid but you have some free space. Putting the 12 bit data in a 8 bit file is like pouring that quart of liquid into a pint container. It won't all fit so you have to throw some away. The main reason to shoot JPEG is that you get more shots on a memory card and it's faster, both in camera and afterwards. If you shoot RAW files you have to then convert them to TIFF or JPEG on a PC before you can view or print them. you have hundreds of images, this can take some time. If you know you have the correct exposure and white balance as well as the optimum camera set parameters, then a high quality JPEG will give you a print just as good as one from a converted RAW file, so you may as well shoot JPEG. You shoot RAW when you expect to have to do some post exposure processing.