In camera processing RAW v JPG comparison

[Stephen]

Originally Posted by Don Hoey

Please post any comments you have on exposing for highlights as this will apply to both RAW and JPEG but with greater implications on JPEG.

Thanks again

Don

Don, it is generally accepted that it is better to expose for the highlights, then bring up the shadows in your image manipulation software.

The two shots below are the same image. The first is an image converted from the Raw file without any adjustment whatsoever, though ACR tells me it was 2.6 stops underexposed. The second is after processing the resulting file in CS2. The image was selectively lightened, and sharpened. I use the polygonal lasso tool and apply a large feather, anything up to 100 pixels,sometimes more, depending on the area I am trying to adjust. It was converted tomono in the channel mixer and toned using colour balance, mainly a bit red and a tad of yellow, its all personal choice.

Now make of them what you will, but the point is that they show that exposing for the highlight saved the image and the amount of information held in the file is suprising.

[Don Hoey]

Originally Posted by Stephen

Don, it is generally accepted that it is better to expose for the highlights, then bring up the shadows in your image manipulation software.

Stephen,

Although you say it is generally accepted, I think you may be supposing some of us know more than we do about digital. I have been treating it as I would have slide film, knew no different until yesterday/today. There is more to digital than first meets the eye. I am learning here, as I would guess are others.

Excellent example. Thank you

Don

[Don Hoey]

Originally Posted by Don Hoey

Stephen,

Although you say it is generally accepted, I think you may be supposing some of us know more than we do about digital. I have been treating it as I would have slide film, knew no different until yesterday/today. There is more to digital than first meets the eye. I am learning here, as I would guess are others.

Stephen,

I will for the purpose here use an anology I saw yesterday to describe my digital knowledge.

For Henri Cartier-Bresson the picture was the most important. Whereas with Ansell Adams it was to an infinite detail the whole process.

I only got my D100 because I forsaw the collapse in residual value of my Bronica kit so I did a straight swap. Photography was no longer a primary interest. That was traction engines and model engineering and last year a bit of bird watching. With the advent of this site I started taking a few pics again other than traction engine rally ones. Processing the image was not the priority as it takes time to learn all the processes.

I had never looked at a histogram as I did not understand them. Today I have read up and had a bit of a play.

That should tell you a bit about my knowledge of digital.
My sceptiscim about some things comes from reading inumerable contradictory comments on the web. Digital is not like film. That would be easy. Someone making extravigant claims could be easily and cheaply checked out.

Don

[Don Hoey]

Firstly let me say that from info in the links posted and Stephens example of what can be done in RAW this is not a RAW v JPEG post.

Stephen will have to excuse me here but there is a need to understand a bit about 8 bit and 16 bit. Also as JPEG is 8 bit the effects of processing on that file.

From a lot of talk on DPR about the softness of images out of the D200 camera and why can't Nikon sort this. This suggests now that these comments are being made without any knowledge of the effects that would have after post processing on the final image. The link from yesterday reasoned that USM is fairly destructive and cannot be undone. All this shows I am not alone in my ignorance of digital.

I could not understand the result from my comparison yesterday, so today I have been a bit more analytical. ( You can crack up now if you want Stephen ). I viewed both images side by side at 1500% and used the colour picker to analyse individual pixel colour. This does show that as tones lighten the difference grows. To my satisfaction this proves 16 bit does retain more colour information.

I have attached 2 images that are screen shots. Firstly just an untouched 16 bit and 8 bit to show how crazy I am. In the second one I applied the same amount of sharpening as I usually do at the end of processing. This showed that now there is even greater differences between 8 bit and 16 bit.

With a new PC and my existing software I will be editing images in 16 bit TIFF.

With that done I am now going to look at best scenario, worst scenario for JPEG as that is 8 bit and my current machine can handle the files.

Don

[Don Hoey]

While I get my head into gear to look at processing a JPEG to its best quality I would like to ask how much members generally crop an image by before printing.

Thanks

Don

[Don Hoey]

While trying to understand those processing effects that are most destructive to JPEG, I returned to this series of articles. http://www.ronbigelow.com/articles/raw2/raw2.htm

Obvious first consideration is to minimise the squares from compression. I have now resorted to looking at the TIFF and JPEG at 5,000% ie each pixel is 10mm square on my screen and I cannot find the effect described here.

Why is the obvious question. Any clues ?

Don

[Don Hoey]

Perhaps I should qualify the previous post. That applies to out of camera JPEGS. In other words with whatever compression JPEG Fine applies.

Don

[robski]

Don refer to post 110 this illustrates the squares from compression. At high quality setting they are not evident. (top) as the quality is reduced (middle and bottom) they become very evident.

Some of the other effects shown in your link apply more to an 8 bit workflow than higher order workflows so you will see the same effects in 8 bit tiff.

[Snowyowl]

I'm completely new to to RAW but my new camera allows me save in RAW and JPEG. I've been doing both so far on the theory that I may learn to use RAW as time goes on and at least the images will be available in that format. My question i; Can anyone recommend a good, straight forward article online that will introduce me to working in RAW?

[Don Hoey]

Originally Posted by Snowyowl

I'm completely new to to RAW but my new camera allows me save in RAW and JPEG. I've been doing both so far on the theory that I may learn to use RAW as time goes on and at least the images will be available in that format. My question i; Can anyone recommend a good, straight forward article online that will introduce me to working in RAW?

Hi Dan,

Looking back to an earlier thread of yours you are using Photoshop 7. http://www.worldphotographyforum.com...read.php?t=544

I know Stephen occasionally visits here and may be able to help as he is a photoshop user. I was earlier trying to help someone, also a photoshop user but was not sure if the links I posted were up to much as I use Paint Shop.

I would guess though that you could still play around in the meantime by converting a RAW image to TIFF and then treating the Tiff image just as you would a JPEG in PS7. Your origional RAW file will still be intact and TIFF is a lossless format so it does not matter how many saves you do. Be aware though that the TIFF file will be about 3 times as large as the RAW file. On my plays with RAW that is how I do it.

The next question is can you open the RAW file to do that ?

Don