RAW versus JPEG

This image was taken just over a year ago and was one of a series of pictures of an old poultry barn not too far from here. In response to my previous post, several folks commented that the HX9V was a pretty good little camera. Yes, perhaps, but when put to the test, as it was here, you can see that it isn’t able to keep up with a full-frame DSLR. The image sensor in the HX9V measures 6.17 X 4.55 mm with an effective resolution of 4608 X 3456 pixels or 16.2 effective MP which means that each light gathering unit has an approximate dimension of 1.33 µm. The image sensor in the D600 measures 35.9 X 24.0 mm with an effective resolution of 6016 × 4016 pixels or 24.3 effective MP which means that each light gathering unit has an approximate dimension of 5.97 µm. Therefore the Nikon has larger light-gathering units and many more of them and this will allow the D600 to take pictures in lower light and to gather much more information than the HX9V. To pursue this further consider that the Sony is not capable of recording images in RAW format, the D600 is. So, what? The following is from a piece which appears at the SLRLounge and it is presented here in an edited form. JPEG files are processed within the camera. While color and exposure are established by your camera settings the camera’s own firmware will process the image to add blacks, contrast, brightness, noise reduction, sharpening and then render the file as a compressed JPEG. Because the image is compressed, JPEG is a “loss” file format, much of the initial image information and detail is discarded and cannot be recovered. You may hear the term “Dynamic Range” used when discussing RAW files vs JPEG. Dynamic Range is simply the amount of tonal range from the darkest shadows to the brightest highlights. Dynamic Range detail in JPEG files is significantly reduced as compared to RAW files. The following is from a piece which appears at the Digital Photography School and it is presented here in an edited form. The major player in the process of image compression is the Discrete Cosine Transformation (DCT) which divides the image into blocks, of usually 8 × 8 pixels, and determines which can be “safely” thrown away because they are less perceivable. And when the image is put back together, a row of 24 pixels that had 24 different tones might now only have 4 or 5. That information is forever lostSo the bottom line to all of this is that JPEG images are much smaller than RAW images (in terms of file size), they look pretty good on your camera’s LCD, and can be taken in very quick succession. RAW files are much larger, take up more room in your camera’s memory card, look only OK on your camera’s LCD, and cannot be taken in very quick succession. Because a RAW file captures more information than a JPEG file the former can produce a final image with much more depth and range. To get the most out of a RAW file however it will require post-processing. JPEG images can be viewed and printed immediately, as is, without any post-processing. Clicking the image here will provide a larger version for you to view. I don’t like to nitpick but the clarity, the depth and the range, simply aren’t up to the standards set by a full-frame DSLR.

Barndoor5

6 thoughts on “RAW versus JPEG

  1. How much petabyte of image data did you already create “in your lifetime”? How do you store and backup them (questions from a paranoid cloud / online backup user … )?

    • You’d think I have lots and lots of it … but I don’t really. But that will change I think, as time goes by. I used to shoot only compressed JPEG files and now I shoot exclusively RAW, and each one of these averages over 20MB. I store several weeks work, including the images I’ve work on, on the Mac and periodically dump stuff to an external drive. I don’t have redundant backups and I’m wondering whether that is wise. If my external drive should crash … I’d lose thousands and thousands of images! My new Mac has a solid state drive (not very high capacity though) which I like and have lots of confidence in. Would you suggest a redundant external drive or the cloud? D

      • I am very paranoid – I don’t rely on any single backup completely incl. “the cloud” and I am backing up anything daily. Cloud providers scan the file repositories for copyright violations and reserve the right to suspend your account in case their scanning software thinks you store music or images illegally. This is rare, but it had happened.

        Thus I copy most data to both additional local locations (other computers, external disk) and a cloud store. Actually a cloud store is my “working directory” so my computer might crash any time and I will not lose data.
        I believe it is important that backups are done automatically – I use my own scripts, but I have seen software solutions for external hard disks e.g. that allow for backing up anything (a pre-defined backup set) on a schedule or when you press one button on the disk.

        I would not worry about hard disk failures only – your computer might also be stolen or it might be damaged by fire, flood or an electrical surge caused by lightning (Actually indirect effects of lightning are rather common – you hardly recognize them… I lost at least one satellite receiver box in this way). Or the data on your internal drive might be damaged by a virus (This cannot be mitigated by a cloud service or anything that provides effectively a real-time mirror of your data… it would be good to have an additional version of the data, a snapshot created a few days before).

        Yes, I know this is paranoid – but it is all about risk management: You rate your assets (the images) and the impact of their damage or loss and the probability of such an event – and design your backup strategy in a way that matches this calculated risk. The efforts of taking backups should match the risks. Probably I have spent too much time analyzing errors in hardware and software and reading about hackers… but I would not underestimate the risks.

  2. This makes more sense than anything I ever read on the subject. Thanks a bunch, Farmer! Now, if you can tell me how to process my RAW files, we’ll be in business 😉 Either my images are just awful, the processing is awful, or I need to upgrade to a D600. Which I would not know how to set anyway. Hopeless, huh? 🙂

    • Come on George! I’ve always thought your images were just fine. You know, I’ll tell ya … when I first ventured into the world of digital reprocessing (and I’m just a beginner) I found, believe it or not, that watching YouTube videos was really helpful. There’s a guy out there by the name of Serge Ramelli (http://www.sergeramelli.com/) who posts lots of very good, fairly short, tutorials online. For example … click this to watch one as an example (http://www.youtube.com/watch?v=-Lp03eoCxf4). I’ve found the tutorials published by Adobe to be way too long and boring. The videos this guy Ramelli does are to-the-point, and I like that. He has certain routines that he applies to every photo he retouches and then there are details added to individual images. There are some fundamentals which are important to know – and he reviews them pretty thoroughly. As far as the D600 goes … it isn’t the camera George that makes the image (I think you’ve told me this yourself before), it’s the eye behind the viewfinder! Can your camera capture images in RAW format? If so, and you’ve been shooting in JPEG, you’ve been missing out on a lot – as far as processing potential goes. If you’ve ever got any questions … feel free to send them my way … always willing to add my two cents. The other thing to keep in mind is that, as far as processing goes, you’re gonna get different opinions on what’s ‘good’ from absolutely every single individual. When I look as the stuff some folks work up, I think to myself “What were they thinking?” and, I’m sure, when some folks look at some of my stuff, they think the very same thing. D

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