Today after a good breakfast
 

The BLT image was taken with Nikon D100 in RAW and JPG to check for any effects on colour. The full image is in my gallery.

The JPG fine image has a file size of 2.91mb.
The RAW converted to JPG has a file size of 6.11mb.

The JPG is slightly lighter than the RAW, but side by side in uncompressed form there does not appear to be any loss of detail.
Attached is a combined image where the only processing has been the raw conversion.

As the combined image had to be compressed I have included a combined image that is a small section of the board and has not had any compression hence the small image. I was quite surprised after my thread starter image how little there is to choose between them.

Not quite up to the standards of DP Review but a good result none the less.

Contributions from anyone with a modern bit of kit would be interesting. After this though, the subject would have to have fine detail that may be lost in highlight areas.

Don

An interesting comparison Don. The toast is a good subject for teasing out the differences in this test. The texture of the bread is distinctly fuzzier in the jpeg, at least it is on my monitor. The wood texture doesn't seem to show as much difference, which is surprising. Overall, there's not much difference but the bread really looks quite different to me.

Duncan.

For in-camera JPEG to be 50% (approx) than that of RAW converted to JPEG suggests the in-camera JPEG must apply more compression than its RAW converted variant. More compression equates to a lower quality image in this case a little softer.

In my test I let NC convert and pass 16-bit TIFF to photoshop then resized whilst just opening in camera JPEG and resizing. The filesize difference was negligible <10%.

I'll do my own colour test using size priority and quality priority JPEG from the D2X tomorrow evening and post the results.

Don, Thanks for posting you and your sandwich, gave me a laugh when stuck in a hotel room yesterday evening :D

Steven, from my earlier look at DPR's review the softness difference between JPG and RAW conversion was put down to the greater processing power of converting RAW in a PC. Given the advances in technology I can understand that. As the JPG file was smaller and the colours lighter I thought that the highlight detail would have suffered. Unfortunately at the time of this shot it was not something I had considered so did not include something suitable in the scene. That is why I did a composite from a section of the board - lightest area in the pic. With both images of the BLT up side by side in uncompressed form, I did not find detail to be missing.

My question to you would be ( as you have the latest kit ) what differences are the between Best Quality JPG and RAW converted straight to JPG. That was the route I took. I did not go RAW through TIFF to JPG.

My interest is that if I know the quality you can get in JPG relative to RAW. Then an upgrade to D200 without an additional PC upgrade may be possible. My current kit could handle the JPG file sizes but not the RAW. I feel from my tests that the differences if there are any, will be in the fine detail in highlight areas.


Don

PS Duncan the JPG is softer its not your screen.

A Quick Colour test with 20D

Colour bars made up in PS and displayed on monitor. Close up of monitor Screen focusing on the green stripe.

Raw file was 9.43Mb
Fine Jpeg was 7.21Mb

Attached is a composite made from 100% crops of jpeg and raw image, no other processing.

Again not a hugh difference, the raw may be slightly better.

Sorry about the patchwork but had problems getting the combined image under 400Kb

Could not sleep for thinking about it then Rob .... Last edited by robski : Today at 02:22. :D

Not up on Canon kit so do not know the release date of your camera, but by comparison with the D100 the file size of your JPEG is BIG. Fine Jpeg was 7.21Mb v D100 JPG fine image has a file size of 2.91mb.

Interesting, thanks for you efforts burning the midnight oil.

Don

Canon 20D was released September 2004.

A D2X in optimum quality JPEG mode does not produce JPEG's as large as 7MB. Filesize is nearer to 3-4MB D2X compressed RAW are 10MB each and uncompressed 20MB!

Edit: The CRT screen image is a challenge to JPEG compression as many edges and rapid spacial changes. I think a reallife JPEG from 20D would produce a filesize much lower.

Yes reallife 20D fine JPEGs are more like 2-4Mb dependent on subject detail.

A little known fact about compression is that with some compression methods it is possible to end up with a bigger file than the original if fed with very rapidly changing information.

You have to remember jpeg in fact uses two forms of compression. A degree of Filtering that throws away image information based on your jpeg encoder setting. After Filtering Huffman compression is then used. Huffman is a lossless compression method.

Another Colour Test
 

I was repairing my big diffuser today and thought a test was in order.

I though a more technical subject was in order this time round. The two composites have only been cropped and compressed to post them here. Softness in the JPG Fine is therefore evident. The larger image had 20% compression and the smaller one 5%.

I have viewed these two side by side at 150 magnification and cannot find any detail that has been lost. Not understanding the technicalities as Rob does I was really pleasantly surprised by the result. So for the D100 there appears to be no percievable quality loss when using JPG.

Don

WOW my back hurts after falling off my chair!

I thought I would repeat my test changing a few factors. Firstly we are looking at 100% crops, on dpreview they use 200% to show difference between JPEG and RAW. I altered in-camera sharpening to 'normal' and did a size priority jpeg and quality priority jpeg. Finally I set RAW compression to OFF. I hoped to give RAW a better comparison.

I looked at the two jpegs and thought, yeah well I will not show the test tonight as its not square, I'll have another go tomorrow. Out of curiosity I converted the RAW and looked at them all 200% then.....BANG - legs in the air and sore lumber region!

I could not believe what I saw, two JPEG's have little in it but look close there is a difference. RAW seems to be picking up the print detail from the label much more than JPEG but when you realise its there, it can be seen. When I looked with my eyes at the tomato's label the printing lines are there, but your own chopped tomatoes from J. Sainsbury's and see.

Shown below is the composite of 100% and the original resized only. To see clearer use photoshop or similar to enlarge the image 200%!

I am considering using uncompressed RAW from now on, and fit thicker carpet and underlay in my office :D