John_F Loc: Minneapolis, MN

There have many posts extolling the superiority of raw image files. I thought I would try a practical test. My data were frim the Sony a6300 set to Raw, 6000 x 4000 pixels. The Sony documentation states each pixel is 14 bits in deprh. So 6000x4000x14/8 is 42,000,000 bytes. So a Sony raw image file must exceed 42 MB, taking into account the file header (file name, checksum, EXIF data, plus other file management data needed by operating system). So I took 7 raw shots of the same object. The SD card was mounted in the card slot of a MacBookPro running El Capitan. The computer operating system must accurately know the file size in order to assign RAM and HD storage space and be able to retrieve the entire file and only the file. Here are the file sizes for the 6000x4000 pixel images.

25,034,752 bytes 1 file
25,067,520 bytes 4 files
25,100,288 bytes 2 files

None of these are anywhere close to 42 MB as 14 bit depth pixels would require. The actual 25 MB file sizes means the pixel bit depths can not exceed 8.

It has been years since I cracked a Solid State physics textbook, but from my remembrance the solid state sensor must be an array of charge traps distributed and 'wired' in an organized way. As light from a subject falls on the sensor some charge traps become charged and others not and the camera firmware translates that information into a digital image file and writes such to the SD card.

My version of Adobe DNG Converter (compatible with Photoshop CS 3 & 4) can not recognise a Sony a6300 .arw fill (it could recognise a Sony a6000 .arw file, tho). But the Apple Preview application could open these a6300 .arw files and could save as TIFF files.

The smallest image file became 144,013,092 bytes. This implies about a bit depth of 46. So Preview has created 46 bits of data from 8.

It seems the .arw file must be some sort of encrypted or compressed file, so are we really getting 'pure' raw image data. Might this make the raw vs jpeg questions just 'so what.'

Rongnongno Loc: FL

And as usual a person who does not understand anything post a crappy analysis.

raw file are compressed or not, a choice made in camera. If you look at size alone a D800e produces a 79mb file uncompressed and when compressed (lossless) it goes down between 35 to 45mb. Because of the smaller size, according to this guy this is not a 14bit raw. Yeah. Right.

As to the last 'conspiracy theory "are we really getting 'pure' raw image data". let me tell you this person just wants to stir trouble.

I am surprised he did not come out with the moronic Nikon 'reduced raw' produced by the camera. THAT is something to complain about (lossy compression).

Longshadow Loc: Audubon, PA, United States

File size probably depends on the information contained about the image. Different images will have different sizes due to what is in the image (how much of what color and where in relationship to adjacent colors, etc.) and the method of data storage. I spot checked some of my raw files and the one group varies between about 20Meg and 26Meg. Not knowing the algorithm by which the information is stored, I doubt that you could predict the size of the file.

DaveHam Loc: Reading UK

The first thing needed here is an understanding of how the camera being tested works. You can set the camera to provide you with a full copy at full size of the image taken; the defaults usually incorporate some file size reduction compressing the data. The manual would be a very good place to start or check on line.

leftyD500 Loc: Ocala, Florida

Are you always this caustic, or are you just having a bad day. Please understand, no one, except for maybe (and in your eyes, I am sure that is a big maybe!) God, is as intelligent as you, so please have mercy on us morons.

davidjt52

Some thoughts from an old but fairly modern photog. First, credentials - pro + semi-pro photog since the mid 70s, pro computer programmer and consultant since 79 specializing in data compression tech. Below is a link to an article from the European Canon site that summarizes the lossless vs. lossy controversy very well. A quick synopsis is, RAW is compressed but in a lossless fashion. JPEG (or other loss-based compression methods such as PNG) are lossy and can easily result in inferior but more convenient image storage. Your job is to experiment and find the dynamic balance point between them on a shot by shot basis. The article does a pretty good (and accurate) job of describing this tech. Also, although from Canon, the tech description applies to pretty much all digital imaging technologies used by all camera software folks. Here's the link:

http://cpn.canon-europe.com/content/education/infobank/image_compression/lossless_and_lossy_compression.do

Hope this helps allay your concerns.

Uuglypher Loc: South Dakota (East River)

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Just a reminder ....As regards brightness spectrum,

1 bit-depth file has two (on/off = white and black) 2 tones of brightness)

2 bits yield four (2^2 = 2x2) : black, dark gray, light gray, white) 4 tones of brightness

3 bits yield eight (2^3 =2x2x2)

4 bits...(2^4) 16 tones of brightness

8 bits (jpeg): 2^8 = 256(tones of brightness)

raw captures may be delivered:

in 12 bit files (2^12.....4096 tones of brightness)

or

14 bit files (2^14... roughly 16,000 tones of brightness.

(to imply that an 8bit-depth JPEG image file delivers image data quality insignificantly different from that of either a 12 bit or 14 bit raw image data capture is....well...ludicrous.

Dave

Jim Bob

Both.

camerapapi Loc: Miami, Fl.

I have this beautiful, full of details 12 bits 79 megabytes file in my computer product of a RAW file. I want a print of it but the professional lab where I take my files tells me that they cannot print RAW files and one of the objections is the wider color space. Their printers are simply not designed to handle any other color space than the moron or stupid sRGB. What do I do now? I have to compress the file to perhaps 45 Megabytes, the 12 bits will go 8 and the wide color space will need conversion to sRGB. What will happen to the original RAW with all these compressions? Although I have been to many workshops and at times (which I hate to do) discuss this with a "professional" I have never received an answer that made me understand what is going on with the conversion.
For many years I shot RAW and my editing was complicated. I was told "RAW is the way to go" to get in the file all of the details and colors I saw. Neither I nor anyone else can see all the colors present in the sRGB color space so imagine the millions of colors of a wide color space. When I have converted from 12 to 8 bits I have not seen a difference and obviously I have not seen a difference comparing a 12 bits RAW with an 8 bits JPEG. If you do your eyes are a gem.
I have said it before and will repeat it again, modern JPEG files are of superb quality. Save them as a TIFF and now you have a lossless file forever. I usually work my JPEGs using a copy of the original and never a problem.
There are plenty of parameters to work and edit JPEG files if needed and yes, in my case I have no issues changing the WB if that pleases me.
I also shoot RAW but not as often as I used to. Those engineers working with software have been doing a great job over the years improving the quality of JPEG files and JPEG files are universal which means that ALL editing softwares will open those files.
These are my observations and I see more and more professionals using JPEG files often. I know of an excellent wedding photographer in the Miami area that only shoots weddings with JPEG files. As far as I know NONE of her customers ever complained of the quality of the photographs.
Do not misunderstand me, I have nothing against shooting RAW if that is what you want to do. I said I use both files but I am shooting JPEG now more often that not.
Just my personal opinion based on my humble experience.

cthahn

Instead of downplaying RAW, which it is obvious you do not understand, take some classes on photography, and learn something. Too many people buy an expensive, purchase the longest zoom they can afford, and call themselves photographers and know nothing about the basics of photography.

Jim Bob

Just the bare facts: RAW collects more data and therefore permits greater flexibility, detail extraction and nuance in post processing. However, whether one can actually consistently see that difference when compared to a properly exposed and/or competently post processed JPEG when viewing popular or common print sizes or on the web is subject to serious debate. Unless we are talking about huge enlargements the difference might be barely perceptible to many. Many UHH posters take offense when asked to show us a difference. They complain that it is not possible given the nature of web based imaging. My response: if you can't show us a difference then what's the point. How many people actually produce mural-sized prints? JPEG processing engines have improved so much that one needs to consider whether the benefits of shooting RAW consistently outweigh the burdens. It's the individual's call.

TheDman Loc: USA

It has nothing to do with being able to create larger prints.

TriX Loc: Raleigh, NC

Google posterization and banding as well as dynamic range for a deeper understanding of why it's beneficial to do post processing on uncompressed files.

glblanchard

You're right, but can't you at least try to be nice occasionally?

BigHal

Shoot RAW, save to a device dedicated to these images (jump drive, external HDD), then pp in Photoshop, save as jpg to a different external device. No pro Lab I know of prints RAW files. I don't believe there exists printers that can print files that big. I realize that this is just a basic answer, but expand your saving procedures to suit your needs and enjoy photography to your heart's content.