Railfan Technology > What's The Difference between RAW and JPEG Images

I have always used JPEG images while taking pictures of trains but, what are the differences between JPEG and RAW pictures anyway? Is RAW better or worse than JPEG? Does RAW take more memory? etc
Thanks in Advance.
Greg



Edited 2 time(s). Last edit at 02/13/12 10:31 by GWHEN.

Pretty basic question, I'll give just a basic answer: Both allow manipulation, but RAW allows MUCH MORE adjustments. JPEG loses quality each and every time you open and save (it compresses each time, losing quality). Raw doesn't. Raw file are MUCH larger than JPEG at best quality, makes them difficult to send in email.

Further study can be done one a thousand web sites designed for instruction.

Ed

Simply speaking, the RAW image is generally full size uncompressed images that are unprocessed (the RAW images are processed on your computer using the supplied software or another photo processing program that can handle RAW images). The JPEG files are processed and compressed in the camera, so some image quality is lost. In the case of a Nikon D90 camera, the compression for a fine quality JPEG is 1:4. RAW is most important if you are going to do some post editing of the image with Photoshop or similar software. You always want to edit an image starting with the largest image size, which would be the RAW image. You can edit the JPEG, but the results are not going to be as good.

You can think of the RAW image as a film negative. It will take up more room on your memory card and your computer hard drive than a JPEG.

Gary



Edited 2 time(s). Last edit at 02/13/12 11:04 by SN711.

Okay thanks for the Information everybody I was just wandering.
Greg

RAW isn't really a standard file format in the sense that JPG is. RAW is really a data dump of all the information that your sensor collects. That's why RAW files vary in format from camera to camera.

A good idea is to consider converting your RAW files to Adobe DNG open format. You lose the ability to use your camera manufacturer's proprietary software, but gain the ability to store your data in an open format that will be supported long after manufacturer's proprietary formats are history.

Oh, Adobe DNG converter is a free download.

~Steve Sloan

consider RAW files as a digital negative. see wiki: http://en.wikipedia.org/wiki/Raw_image_format

chico
http://www.heartlandrails.com

It can be thought of that way, in the sense that a negative is an intermediate between the capture of the image and the final product: the display of an image. It is not a negative in the sense of film where a negative is the photographic opposite of a positive.

Used this same way, a 16 bit TIFF scan of an analog image (slide or film neg) is also a digital negative. Also, if your printing, so is any jpeg if your output is paper.

~Steve Sloan

ssloansjca Wrote:
-------------------------------------------------------
> It can be thought of that way, in the sense that a
> negative is an intermediate between the capture of
> the image and the final product: the display of an
> image. It is not a negative in the sense of film
> where a negative is the photographic opposite of a
> positive.
>
> Used this same way, a 16 bit TIFF scan of an
> analog image (slide or film neg) is also a digital
> negative. Also, if your printing, so is any jpeg
> if your output is paper.
>
> ~Steve Sloan

Steve, have you thought about going to law school?

lol

chico
http://www.heartlandrails.com

Yes, I did, think about law school that is. I finally got my BA in Journalism and my master's in Education.

Never got my PhD though.

~Steve

I shoot everything in RAW format with my Canon 400D. Adobe Photoshop CS5 reads the camera's RAW image files so I don't need, nor have any of the Canon software installed on my computer. Here's how I prepare my images. I take the RAW image and open it in Adobe CameraRaw which comes with Photoshop. I start processing the image there and make adjustments then open the file in Photoshop. I then save the photo as an Adobe Photoshop .PSD file in a different folder from the RAW image, I then make a JPEG from that. I've been doing this for as long as I've done digital photography and was doing the same thing with film where I would scan the slide or negative, save the file as a .PSD file then create a JPEG from that. Never had a problem!

A little amplification of that first step -- opening the image up in Adobe CameraRaw for processing: Adobe's software knows what camera, exposure details (aperture, shutter, etc.) and even what lens (if DSLR camera) the photo was taken with. You can actually adjust White Balance, Exposure, apply Lens Correction (Chromatic Aberration, Vignetting) and so on. Then when you're satisfied at that point, go ahead and open up the file in Photoshop itself. The changes you've made do not permanently affect the RAW file; they're stored separately in a companion file that Adobe creates.

Adding to the discussion:
Has anyone had experience with the Adobe DNG format? If I'm not mistaken, it's a feature of the Adobe Lightroom program.

Thanks in advance for any info.

Have fun, be safe,
Doc Jones

The beauty of DNG is it acts in every way like a RAW file, only better. It is not a proprietary format so if a camera manufacturer stops supporting the format, you are not screwed. And, it does not depend on companion files, that can get separated by file systems from their parent files. A DNG is a container that holds all the original data from the raw file and the metadata applied by programs like Lightroom and Adobe Camera Raw's processing engine in Photoshop.

When I am teaching Photoshop courses, I encourage my students to consider converting everything into DNG if they are using an Adobe workflow.

~Steve

I have a workflow defined in Adobe Lightroom that when I capture from the Camera converts Canon raw (.cr2) to .dng as part of the import, and also applies a chromatic aberration correction specific to the lens I use. Then I work with the .dng files in Lightroom. Adobe also has a downloadable codec that allows the .dng images to be viewed in Windows. I like .dng, but any raw format gives much greater ability to work with the image than jpg, as stated above. When I want to post something, I almost always go back to the original raw image and re-edit, because my preferences in editing change over time and hopefully I learn stuff and get better at it as time goes by. That's the theory, anyway.

Jim B