Advanced cameras can capture and save images in JPEG as well as RAW formats. Though RAW format consumes more carpet area on your memory card, it is wonderful and may I say, the only option for post-processing. Let's have a look at why JPEGs are bad for post-processing/image correction.
How does the digital camera create an image?
Your camera sensor senses the incident light along with its different aspects like brightness, contrast, hue, the colors in it and many other things and applies a sophisticated algorithm to process all this detail and save it as an image on your memory card. This image can be saved with a lot of information or with minimal information so as to reduce the file size. If you save all the information possible, you can then selectively remove/polish/modify selective aspects of the saved image in an image editing program to yield desired results. If you remove much of the information and retail only as much as required for the image to be created with near-to-real reproduction, then you would achieve a much smaller sized email image which you can't do almost any post-production on. The previous type of image is called a loss-less image (RAW for example) while the other type is called a lossy image (JPEG).
What is a JPEG?
JPEGs were created as a web-friendly solution for images. Before JPEGs came into existence, the world worked with BMP images (which are quite rare these days but if you had a windows 95 PC, it did not recognize JPEGs; you had to install special software to work with JPEGs) which is an acronym for BITMAP. In BMP images, each pixel's color information was saved in the file. So if you have 1024x768 pixels in the image and each pixel took x bytes to save, you'd end up with 786432x bytes for one image. I remember BMP commonly weighing between 4-10 MB each. You can't have such heavy images on a webpage!
Enter the JPEG! It's an acronym which stand for Joint Photographic Experts Group, the geniuses who used their mathematical prowess to revolutionize image persistence and shrunk the 4MB BMP to a 100KB JPG!
Because JPEG employs a lossy compression technique, every time you open a JPEG and save it through a CTRL+S, it is compressed and saved. So each save compresses it further and leads to a further reduction in detail. So if you want to photoshop your images, JPEGs are not the ideal solution even if you save them in the highest resolution possible.
Lay it RAW!
RAW is not an acronym - it simple hints at the fact that the image has undergone minimal processing between the point of capture (sensor) and point of save (memory card). As such, it contains maximum optical information possible. Each manufacturer has his own RAW file format which needs you to install manufacturer-specific software/drivers to view the RAW image. Nikon uses the NEF file extension while Canon uses the CR2 extension.
Why should I use RAW?
There are multiple reasons for which you should shoot in RAW provided you are adept at using post-processing tools like GIMP/Photoshop or any other sophisticated image editing software.
- White balance correction: if you have shot an image with incorrect whitebalance settings, you can use a RAW editing program to make the correction. In the below image, the upper section has correct whitebalance while the lower one has a warm tinge.
|Image Courtesy: phottix.com|
- Exposure correction: if you image is over/under-exposed, you can make corrections to get correct exposure. The below screenshot shows an over-exposed sky in the RAW image at the bottom with the corrected sky above it. This level of exposure correction is not possible in JPEGs.
|Image Courtesy: kelbymediagroup.com|
- JPEGs store information in 8bit format while RAW store in 12 to 16 bit format which leads to an amazing difference in the quality of image detail. Due to this, any of the processing done to a RAW file yields a better final image as compared to changes done to a JPEG.
- Many alterations/corrections like brightness, saturation, hue, contrast, color correction, gamma correction, sharpening, noise reduction, etc should be ideally performed on RAW images only.
Ok what's the catch?
With all due respect, RAW is not for everybody. Don't shoot in RAW just because I said it yields better and sharper images. If you don't intend to do post-processing on it, it's just not worth the hassle since you will be simply converting them to JPEGs for circulation/distribution and you personal archive anyway :p
- RAW needs manufacturer specific drivers/software installed to read the RAW file. For example, windows cannot read the NEF file (Nikon). You can access it through Nikon's RAW software or through third party tools like Adobe Lightroom which is a RAW editing software.
- File size: RAW files are typically 4-6 times the size of the biggest JPEG that your camera can save. That means 1/4th-1/6th the number of photos that your camera can save. So if your card can save a max of 100 JPEGs of the highest resolution, it can save less than 25 RAW files!
- RAW process workflow takes up quite some time for even the simplest operations: if you shoot 200 images in your brother's wedding and need to load them in a RAW processing tool, make corrections to them and save as JPEG - you'd need a fast processor, multiple hands like a demigod and multiple screens on which you can execute this shit in parallel to get it done in one day! It takes me upto a week to process RAW images of one photoshoot!
- And of course, you need sufficient knowledge about the RAW processing tool too!
I shoot in RAW, process in Lightroom and then polish in Photoshop to finally achieve the desired JPEG. Each image takes anywhere between 45-90 mins. You don't need to treat each image with such tender care and loving but if you have that kind of patience, stay RAW!