Since shooting stock for DT, I have been on a learning curve. Learning about ISO, DOF, Dynamic Range, Histograms and tons of other fun stuff that makes me feel more like a technician of imagery than a photographer. I deal with reality (photography) first and that’s to capture the image creatively, after that reality ends and technology begins.
This latest curve for me is compression of files. DSLR cameras store files in two formats: Lossless Compression and Lossy Compression. OK, that’s it that’s all I need to know, how easier can that be to pick the right file format for my images? Who wants lossy compressions? Well becoming the wizard of technology I have to know what that means in digital numbers. That’s what we have become, right, accounting photographers, having to keep track of all the numbers associated with the digital photography.
When I capture an image on a sensor it is processed and sent to the memory card. How much image data I keep and save to my memory card depends on how the DSLR formats my files. The more data I keep the more numbers to store and that means more space needed to store the captured images. I use 4G memory cards with a buffer to keep up with storage. I do keep a few memory cards in my bag so I will never run out of memory.
The two file formats I have to choose from are either RAW and JPEG.
1) RAW a Lossless Compression format. RAW captures everything the senor sees and loses no data, giving me more flexibility over the finished image. RAW files normally hold 14-bit or more of color information for post-processing and therefore the files are rather on the large size. RAW files have more information then JPEG files, but this does not eliminate noise. Most noise is generated after the image is captured by the camera’s senor and is being transfer to the memory card.
RAW files are unprocessed by the DSLR while the JPEG is corrected for image tone, color, sharpness, and WB all before saving it to memory card. With RAW files I can control all these corrections after downloading to computer.
RAW files are converted by software to either TIFF or JPEG. The TIFF file is a lossless compression file that can be opened and edit numerous times without loss to the original contents of the file. The DSLR camera manufacture includes software for converting RAW into TIFF OR JPEG files suitable for editing.
2) JPEG a Lossy Compression format. JPEG files are normally 8-bit of color information and do not require post-processing for printing from. JPEG will lose some quality but requires no post-processing like RAW files. But will gain some noise over the RAW because of the downsizing of the file from 14-bit to 8-bit as well as the corrections to the image. JPEG files discard information each time the file is opened, edited and saved.
Each has its place in my capturing of images, but it’s nice to know what my choices are. I have chosen to do both RAW and JPEG since my camera has that feature and it's faster to review the JPEG files on my computers.