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Tuesday, December 6, 2011

RAW vs JPEG file showdown

Well some times I get mails and questions like ....  keep hearing about something called RAW what is a Raw file ??? Should I use the RAW mode of my camera ??? RAW mode is slow why should I use it.. Jpeg or RAW which is the best and why ???

OK so here we go ...

What is a JPEG file:

Simple answer: A graphic file type that is almost universal and can be opened anywhere. Is small in size. Offers good to decent image quality.

Technical answer: The name "JPEG" stands for Joint Photographic Experts Group, the name of the committee that created the JPEG standard and also other standards. The JPEG standard specifies the codec. A codec is a device or computer program capable of encoding or decoding a digital data stream or signal. The word codec is a portmanteau of "compressor-decompressor" or, more commonly, "coder-decoder".

Which defines how an image is compressed into a stream of bytes and decompressed back into an image, but not the file format used to contain that stream. The compression method is usually lossy, meaning that some original image information is lost and cannot be restored, affecting image quality. There is an optional lossless mode defined in the JPEG standard; however, that mode is not widely supported in software products.

What does a JPEG file contain: 
  •     Color space definition
  •     Component sub-sampling registration
  •     Pixel aspect ratio definition.
What is RAW file:

Simple answer: A graphic file type that is different for each company or even camera model no. (e.g Canon .CRW and .CR2 files). RAW files are much bigger in size. Offers the best image quality. RAW files require special software to open and edit. A camera raw image file contains minimally processed data from the image sensor. Raw files are so named because they are not yet processed and therefore are not ready to be printed or edited. Normally, the image is processed by a raw converter software.

Technical answer: Raw image formats are intended to capture as closely as possible (i.e. at the best of the specific sensor's performance) the radiometric characteristics of the scene, that is, physical information about the light intensity and color of the scene. Most raw image file formats store information sensed according to the geometry of the sensor's individual photo-receptive elements sometimes called pixels rather than points in the expected final image: sensors with hexagonal element displacement, for example, record information for each of their hexagonally-displaced cells, which a decoding software will eventually transform into the rectangular geometry during "digital developing".

Raw image files are sometimes called digital negatives, as they fulfill the same role as negatives in film photography: that is, the negative is not directly usable as an image, but has all of the information needed to create an image. Likewise, the process of converting a raw image file into a viewable format is sometimes called developing a raw image, by analogy with the film development process used to convert photographic film into viewable prints. The selection of the final choice of image rendering is part of the process of white balancing and color grading. Like a photographic negative, a raw digital image have a wider dynamic range or color gamut than the eventual final image format, and it preserves most of the information of the captured image. The purpose of raw image formats is to save, with minimum loss of information, data obtained from the sensor, and the conditions surrounding the capturing of the image.

What does a RAW file contain:

  • A short file header which typically contains an indicator of the byte-ordering of the file, a file identifier and an offset into the main file data.
  • Camera sensor metadata which is required to interpret the sensor image data. This includes the size of the sensor, the attributes of the CFA and its color profile.
  • Image metadata which is required for inclusion in any CMS environment or database. These include the exposure settings, camera/scanner/lens model, date (and, optionally,place) of shoot/scan, authoring information and other. Some raw files contain a standardized metadata section with data in Exif format.
  • An image thumbnail. Optionally a reduced-size image in JPEG format, which can be used for a quick and less computing-intensive preview.
  • The sensor image data
Ok all this info is awesome and all but, too much info and computer tech doodle. Can you give me some simple easy to use information ;) ...Sure

JPEG versus RAW:
JPEGs are:
Faster to shoot
Faster to Save
Smaller in file size, consequently you can save many more panos/images on a drive.
Can be opened/edited in just about any graphics program
Little or no learning curve
Anyone or almost any camera can shoot JPGs
8-bit files (only 256 color per channel)
Limited ability to color correct
Generally, you need to bracket in ONE f-stop increments.
Very limited in overall detail, but especially in highlight and shadow details
(in other words dark areas go black quickly and highlights go completely white quickly)
Better for shooting "journalistic" or fast moving/changing scenes, especially with people in them.

RAW files are:

Slower to shoot
Slower to save (More bits = bigger file size = more hard drive space needed = less images can be saved to a hard drive)
Larger in file size (14-bit RAWs are about 25% larger than 12-bit RAWs)
12-bit files have 4096 colors per channel and 14-bit files have 16,384!
Are "proprietary" per camera manufacturer and even within a single manufacturer
(i.e.: Canon) they have multiple RAW formats (i.e.: .CR2 and .CRW)
Much more exposure latitude, consequently fewer photos to cover a large exposure range.
(i.e. 3 RAW files can cover a range that 5 or 6 jpegs would be needed to cover)
This also means less bracketing!
Ability to change color temperature after its been shot.
Have to be "processed" in a digital darkroom (i.e.: Adobe Lightroom) and then saved as secondary file such as Tiff, JPG, EXR, etc.
Are Non-destructive! At this point, RAW files cannot be saved. Therefore you can always go back to the original and make additional corrections.
Are naturally a bit "soft" looking. RAW files are INTENDED to be sharpened, so some photographers have a hard time switching for that reason alone.

**Special note -- Cameras with a small sensor size like many Pro zoomers and Four-micro systems. Using ISO speeds of over 800 or more generally results in bad quality or lot of digital noise. Using a RAW file will always give you better results after De-nosing/noise removal than using a jpeg.

In terms of colors, what is the difference between 8-bit, 12-bit, 14-bit, and 16-bit files?
    • 8-bit files: 256 colors (shades of gray) per RGB channel
    • 12-bit files: 4,096 colors (shades of gray) per RGB channel
    • 14-bit files: 16,384 (shades of gray) per RGB channel
    • 16-bit files: 65,536 colors (shades of gray) per RGB channel

Cool so still why use RAW ??
In terms of practical application, having more bits per channel basically means more subtle/smoother color variations, more highlight, and more shadow details are
available.This simply means that you will have more rich and bright, vibrant colors = better looking photographs. Personally, I always try and shoot RAW. Once you go RAW, you never want to go back to the “old” way. (Assuming you know how to properly process them)

Nice how do I start with RAW files and what software is needed???

Set your camera to RAW mode. Start shooting. For basic simple level editing of RAW files use IrfanView free get it at http://www.irfanview.com/

For proper full "processed" RAW file in a digital darkroom use Adobe Lightroom or
Raw Therapee free get it at http://rawtherapee.com/

Then saved as secondary file such as Tiff, JPG, EXR, PNG.
I recommend using PNG over JPG much better quality and decent file size.

Why not use RAW files ??
You have a old and slow computer.
Full and proper RAW processing requires a fast computer with lots of RAM.
RAW files take a lot of space, so if you are running out of disk space it is better to use JPEG.
You mainly shoot to upload the photos online, best possible quality is not an absolute requirement.
You do not want to learn new software and do any type of digital processing.
Developing/Processing RAW files is a time consuming activity. Which may lead to excessive consumption of Coffee, jolt cola, red bull and other such energy drinks ;)
You are pressed for time, you just need basic edit, crop, save. Use jpeg
You are just plain lazy ;)

Disclaimer: Parts of this post were sourced from the Internet and placed here for easy and quick reference.