In camera processing RAW v JPG comparison

[Don Hoey]

Originally Posted by Saphire

I agree Don its a personal thing but once it has been put in your head that something is inferior it sticks and that is what made me change I couldn't shake it. every time I had a bad photo it was niggling as to whether I would have got a better photo shooting raw, utter nonsense I know, so decided, I wanted to be in control and not the equipment deciding for me.

Not really nonsense Christine as RAW does give you that greater degree of control.

If you go back to the total newbie part the whole thing is quite daunting. In the days of film it was just a matter of understanding how the camera worked ..... and how many books have been written on that subject !! Now if you have to learn both it is a very steep learning curve. Quite natural for any newbie to use jpeg while they learn the camera. If someone then says jpeg is rubbish and lots better results from raw, then the gloss starts to be taken off the new found hobby, ( see post 75 ). Now probably too much to take on board. In time as knowledge increases so people may well move to raw for that level of control.

My case was purely budget driven. A move up could involve a new PC and camera in one go. LOADSA MONEY ££££££££££££££ so could this be spread in favour of camera first rather than last.

Don

[Stephen]

Originally Posted by Don Hoey

My case was purely budget driven. A move up could involve a new PC and camera in one go. LOADSA MONEY ££££££££££££££ so could this be spread in favour of camera first rather than last.

Don

Don, I can understand your desire to trade up and consequently the need to do the same with the PC, I have been there too However if funds are limited it seems to me that the best bet is to go for the PC first. It will improve your digital experience with the post processing and software 100% The D100, though long in the tooth perhaps, still takes as good a picture as it always did, and will continue to do so. If its more pixels you want it is possible to achieve this in the Raw conversion without a discernable loss in quality. The power of a new faster PC is going to make it more pleasurable to do so. Only my opinion you understand

[Tannin]

It's all about the trade-offs you are willing and not willing to make. Raw and JPEG both involve making a trade-off, and it is up to all of us to make our own decisions as to which is the lesser of two evils.

For me, most of the time, I stand a better chance of getting better pictures with JPEG - raw doesn't allow me rapid enough shutter repeats, and puts constraints on the time I can spend in the field (because of the vastly increased processing time and the storage problem).

For the next person, the opposite applies. If, for example, I mostly did landscapes, I'd mostly shoot raw for the extra flexibility it allows in PP. But for bird work, especially action shots, the ability to ripple off a long series of frames without delay is crucial. Yes, I have to get the white balance and exposure right first time but that is, in my case, the lesser evil and results in fewer missed shots. Your case may differ, of course.

Summary: don't stress out about what other people do and say, just find out what works best for you and get on with taking great pictures.

[Don Hoey]

Originally Posted by Stephen

If its more pixels you want it is possible to achieve this in the Raw conversion without a discernable loss in quality. The power of a new faster PC is going to make it more pleasurable to do so. Only my opinion you understand

Stephen,

Another thing I do not understand here. ( Relativly new to digital - lots to learn )
When Stephen ( Fox ) and I were doing tests on how colours are processed he fired me 2 pics. D2X ( 12mp ) and D70 ( 6mp ) included in the shot was a pilots map. The fine detail in that map is more detailed from the D2X as expected. If these images contain all the information that the sensor can record how can this be increased.

Coming from the world of film it is to me like moving to a finer grain film. Finer grain film = more resolution. ( ie I used to shoot Technical Pan a lot on 6x6 )

So is what you describe just an upsizing of the image o/a dimensions, or an image quality improvement ?

Don

[Stephen]

Originally Posted by Don Hoey

Stephen,

Another thing I do not understand here. ( Relativly new to digital - lots to learn )
When Stephen ( Fox ) and I were doing tests on how colours are processed he fired me 2 pics. D2X ( 12mp ) and D70 ( 6mp ) included in the shot was a pilots map. The fine detail in that map is more detailed from the D2X as expected. If these images contain all the information that the sensor can record how can this be increased.

Coming from the world of film it is to me like moving to a finer grain film. Finer grain film = more resolution. ( ie I used to shoot Technical Pan a lot on 6x6 )

So is what you describe just an upsizing of the image o/a dimensions, or an image quality improvement ?

Don

Don I too came from a world of film, using 6x6 a lot of the time, however I used mainly ISO400 film. I'm a real world photographer and I knew that medium format images printed to the sizes that most customers demanded were fine on such film. No one was ever going to tell the difference at say 7x5 or 10x8 ISO400 gave me the flexibility I needed to fulfil most work. If I was using transparency film on a brochure shoot then ISO 100 would have likely been used. In the studio too 100 was the norm. However being a real world photographer I knew that 99% of the time no one needed the quality afforded by MF and fine grain films. Doing product photography, which I rarely do however, and it may be a different case.

Now thankfully I haven't used film for about 7 years now. I never want to go back to those days when I lost control of the process after pressing the shutter. In the case of B/W, I don't want to spend hours in a darkroom, enjoyable as it occasionally was. I am using an 8.2mp camera atm. and I know because I'm a real world photographer that most of the time the file sizes I produce are far bigger than is really needed. The photosI take contain all the detail that is needed, prints are pin sharp, colours vibrant and accurate etc etc. I have been in full control from visualisation through to the finished product.

However if the circumstances dictate that I need that extra resolution, as happened the other week where I need to crop some images, I can then upsize the image in the raw conversion which will give me the larger file size I may need. Because I'm a real world photographer I know that so far as the client is concerned the end product is all that matters and so long as they get a quality product they are happy. I know I can do this upsizing and have a print produced poster size with no dicernable loss in quality. I don't need to look at pixels and 200% crops to know what is good and what is not.

For me the workflow is to use PS CS2 and Adobe Camera Raw. The screen grab attached shows the ACR dialogue with the resolution menu open, and you can see the options available when processing your file. My theory is that its better to upsize in ACR or at this stage, because you are interpolating effectively a file that has still not had its final condition decided. Whilst if it was upsized from a jpeg this is another stage. I've not personally tested the theory, but then I'm not a 'measurebator' I just know that this works for me and the end product speaks for itself. Its what being a real world photographer is all about

[Tannin]

OK, I'll bite on that one. Assume, for the moment, equal detail in your JPEG and your raw (and for that matter your BMP and your PNG and your TIFF) versions of the image. So far as detail goes, you cannot get a better upres from any of those formats than you get from any of the other formats - the information that is contained in the image is the information that is contained in the image. End of story.

The real question, then, is do the different image versions contain equal detail or not?

[Stephen]

Originally Posted by Tannin

OK, I'll bite on that one. Assume, for the moment, equal detail in your JPEG and your raw (and for that matter your BMP and your PNG and your TIFF) versions of the image. So far as detail goes, you cannot get a better upres from any of those formats than you get from any of the other formats - the information that is contained in the image is the information that is contained in the image. End of story.

The real question, then, is do the different image versions contain equal detail or not?

Its a difficult one innit
Personally I think your original premis is flawed. A jpeg file does not necessarilly contain the same detail, as we know up to 75% of the pixels have been chucked away, only to be put pack as a best guess when reopened.

If you upsize this then logically you are in theory interpolating data that wasn't in the original file. Upsizing during the raw conversion is, it seems to me, interpolating data that the camera created and recorded, and consequently it follows that potentially it will retain more detail.

I suppose an alternative method would be to convert to a TIFF then upsize from that. I really don't want to get into the physics of it too much though. I'm more bothered about what works for me, I'm not suggesting that all 6mp raw files should be upsized as a matter of course, that would be a nonsense. Fujifilm of course designed cameras round the principle

[Tannin]

An interesting discussion, Stephen.

Ahhh ... but that's the thing: a JPEG doesn't throw away 75% of the pixels. JPEG compression, at least as as I understand it, retains every pixel. What it does is throw away some of the colour information (on the theory that the human eye is quite good at telling the difference between different brightness levels, but not very good at detecting fine graduations in colour).

So have we lost information? Yes.

Have we lost useful information? Probably not. After all, our output devices (graphics cards, screens, LCD screens in particular, printers, and projectors - especially LCD projectors) are not very good at reproducing fine graduations in colour in any case.

I guess the next step is to try an actual experiment. (And I won't for one moment criticise what works for you - if it's working, don't even think about changing it!)

But speaking of beautiful colours, I think it's time I posted a picture of the Gang Gang Cockatoo I saw the other day, just because she was indeed so beatiful. I'm off to the gallery.

[Stephen]

Originally Posted by Tannin

An interesting discussion, Stephen.

Ahhh ... but that's the thing: a JPEG doesn't throw away 75% of the pixels. JPEG compression, at least as as I understand it, retains every pixel. What it does is throw away some of the colour information (on the theory that the human eye is quite good at telling the difference between different brightness levels, but not very good at detecting fine graduations in colour).

Ah you are right, wrong use of techical terms on my part What I should have referred to is the loss of data as in bytes. It is this of course that allows the file to be reduced in size. The fact is as well that this loss will lead to jpeg artefacts etc over time. I did read however that someone had opened and resaved a jpeg file many many times at max quality 12 in PS and had not found any dicernable loss in quality.

[robski]

Originally Posted by Stephen

A jpeg file does not necessarilly contain the same detail, as we know up to 75% of the pixels have been chucked away, only to be put back as a best guess when reopened.

I see we are sliding back into the realms of rhetoric. This statement maybe fair if the jpeg encoder is set with co-efficients to give extreme compression but in our case we are talking about using the best quality setting available. (it is possible to have finer setting but this would not give any worth while compression and lossless techniques would be better) For my sins I have had to get my head around the internal workings of the jpeg encoder in my line of work.

My interest in this thread had been to gain enough insight to see whether it is worth investing in more hardware to use RAW effectively. Does it give me enough latitude to correct problem shots. Many have talked about the improved sharpness which has not been my experience. I can see from some examples in this thread there is a difference but I believe some models of camera seem to blur the image before passing to jpeg encoder. This approach would achieve smaller files. I have dabbled with RAW and to date I have not been that impressed. I downloaded a freebie RAW converter that crashed all the time. I now have PS CS1 and with blown highlights on bird shots it failed to improve. The other pain was the Canon 300D it did not save RAW + jpeg. Because small birds move so quickly many shots are trashed and a quick method of proofing was required. So I reverted back to using jpeg. Now I have the 20D which will save RAW + jpeg I am willing to try RAW again but need to be convinced by example that it is really worth the effort and expense.

The jpeg process works by splitting the image into it’s chroma and luminance components ( colour & B/W). A transform is performed on these to determine how many levels of detail are in the image. This is similar to determining what sound frequencies exist in a piece of music. Depending on your jpeg encoder settings it first removes the high frequency components from the chroma and then as the level of compression is increased to extreme levels it starts to work on the luminance channel.
The remaining data is then compressed using standard lossless compression methods.

I have attached an example created in PS of low (fine)(top), medium and extreme (bottom) compression settings. I have zoomed the image to show the jpeg artifacts at each level. The low-fine setting usually uses co-efficients that give a useful compression before the jpeg artifacts start to show. I have compared the colour accuraracy between the original and the fine version and the difference in pixel values is about 0.5% with no noticeable overlap in colour.