RAW Convertor Comparison

Myself and a photography friend used three different mainstream RAW convertors to examine 'stair stepping', detail and neutrality on some 1DsIII files. The test image was an image that had good dynamic range and fine detail. The results were very surprising. We used DPP, Lightroom / ACR and Capture One 4. The IDsIII was shot using a Contax 35-70 f3.3 lens, far sharper than anything Canon has produced to pull as much detail as possible out of the sensor. There were no exposure or colour alterations to the files in any way, just straight conversions with the same levels of capture sharpening applied to each.

From our conclusions the Adobe engine showed the most prominent stair stepping, then DPP. The Capture One engine mas so clean it was almsot unnoticeable.
The second surprise was that DPP and Lightroom / ACR produced considerably warmer tones and DPP produced higher saturation in their conversions, whereas the C1 looked very neutral if a little under exposed when compared to the other two.
Despite the fact that the highlights were not clipped in camera, DPP blew the highlights very slightly, whereas the others remained remarkably consistant to the graph in camera and before conversion. The Lightroom conversion looked the lighter of the three in midtones.

Sorry if this is old news, I thought I would share it anyway for as 'which RAW converter?' posts do crop up time and time again. I am not conducting a Galbraith level test as I am no expert, it was just a little late night testing, but it amazed me the difference between RAW converters.

Can anyone else add their findings to this? I would be interested to read them...

David

Here's the first image, look at the colour especially in the sky.

Here's the stair stepping I was on about. I gather that for bird feathers / architecture etc this could be a big issue. I am sorry but at this reduced file size JPEG is causing stepping on all of them, in the full size images stair stepping cannot be seen in the Capture One image and only just in the DPP. Also If you look at the windows in particular, to my eye Lightroom pulls out the worst level of fine detail but that may be just me....

Perhaps if you display the images at 200% or 400% and do a screen capture, the jpeg compression will not hide what you're trying to show.

It's certainly true that different raw converters use different demosaicing algorithms, and default amounts of sharpening and noise reduction, and so will exhibit differences at fine scales.

Looking at the sky in both the ACR and Cap One shots, the adobe just looks to be brighter/more exposed than the cap one shot, hence the sky looks more blown/less detail. I have both and am not convinced one does a better job than the other (ACR vs. Phase One). I think alot has to do with the control and user interface differences available for conversion. I haven't tried Cap One 4 in a while, so perhaps on a rainy day I will take another look at C14. I have been extremely happy with ACR conversions.

Just to reiterate there were no alterations to any files in any of the RAW converters, just a straight conversion with capture sharpening.

Exactly, you are comparing various raw converters at default settings.
However, different converters will have different brightness/exposure settings at their defaults. Same with color and sharpening. Hence the differences.

The examples show the differences in colour and exposure between these RAW converters' default settings, which may be of interest to those who were unaware of these differences. Therefore different styles of image, or particular subjects (eg. landscape vs wildlife), may benefit from the use of a particular RAW converter to bring out the best in the image.

However, most importantly they clearly show that Adobe Lightroom introduces quite pronounced (to my eyes) stair-stepping compared to the other two. I find DPP better, but Capture One is by far the best at avoiding these horrible looking artifacts.
As David rightly points out, their detrimental effect on subject matter such as bird feathers and architechture can be considerable. Even if it is not immediately obvious to the casual viewer, it will still effect their perception of the overall image.

Whilst these small details may not be important to some, those coughing up large sums for a 1DS MKIII in trying to achieve the highest image quality for large gallery prints etc. may be surprised at the differences. If interpollation of an image is required it can become very important indeed.

David,

Before this is discussed any furhter, perhaps a brief definition of "stairstepping" should be posted for those that might not know what to look for. Just a thought.

Thanks.

Wayne, you read my mind. I have no idea what's wrong with those close-ups, and see very little to choose between any of them, except that maybe Lightroom's exposure should be pulled back a bit. Can someone explain what I should be seeing as far as "stairstepping"?

Look at the telephone wire, lightroom turns curves into steps. a jagged line. This is a lot less agressive in DPP but even less noticeable in C1. This is the RAW convertor and not the camera.

Hate to keep beating a dead horse but, as Eric said it is important to realize that these comparisons are based on the default settings of the RAW converter. The default settings of each converter may have been set by each company for different types of images. By adjusting the settings it is very likely that each image would be improved. Adjusting those settings DO NOT degrade image quality and it is the final image that is important.

I assumed it was the line.

Steve is right that these should be evaluated with the knowledge that they are viewed at the default settings.

What change of setting would then improve upon this stair stepping effect that David has shown in his examples? That seems to be something that you couldn't adjust out--or am I missing something?

Paul

pleverington wrote:What change of setting would then improve upon this stair stepping effect that David has shown in his examples? That seems to be something that you couldn't adjust out--or am I missing something?

Paul

I suspect that decreasing the sharpening would remove the stair stepping. ACR may have a more aggressive sharpening as a default compared to Capture1. Perhaps someone who uses both could confirm this.

I think it has nothing to do with default sharpening settings, as I've tried this at various sharpening levels in all these converters.
When the sharpness of the rest of the image is essentially identical, the stair-stepping (not just on curves but also on some angled straight lines) is very noticeable in Lightroom, less so in DPP and not at all in C1 - when the rest of the image is equally sharpened.

I suppose if you can't see it then it won't matter to you, but once you've noticed the problem it just leaps up off the image. I don't use ACR or Lightroom because this problem spoils the image for me. YMMV.

Well if you have a raw file you can post I'd be happy to give it a try myself at various sharpening levels.

I use both Capture and ACR, and Capture's default sharpening setting is much higher than ACR's. Also, I do not get this "stair stepping" in either Capture or ACR. Those are the only RAW converters I have ever used, and both work great for me.