In part 1 of this series, I promised to show the tone curves for the various raw developers that I'm looking at. Here they are:


The Lightroom curves, for various settings of brightness and contrast - brightness has by far the most pronounced impact the image. In Lightroom, to get to a linear curve, you need to do three things - set brightness to zero, set contrast to zero, and select "Tone Curve - Flat" from the presets.


Then the Aperture curve showing the effect of the Aperture boost setting; the effect is essentially the same as the Lightroom brightness setting. To get a linear curve from Aperture, all you have to do is to set boost to zero.


Finally, the Capture One V4 setting; Capture One is a bit different to Lightroom and Aperture. Where Lightroom and Aperture have slider settings that are non-zero by default (brightness and boost respectively), on Capture One all settings default to zero. However, also by default, Capture One loads a "Film Standard" tone curve, which has a very similar effect to the other two program's non-zero settings. To get rid of the curve, all you need to do is to select the "Linear Response" Curve setting.


The last set of curves show a comparison of the default curve for each program, all referred back to a sRGB/2.2 gamma curve to make them comparable. While all the curves are about the same shape, there's a distinct difference in the "aggressiveness" of each curve. Lightroom/ACR adds the most brightness in the mid tones, and Capture One the least, and Aperture's about in the middle. We'll come back to this issue later in this series, but the next step is to use these tone curves to allow us to calibrate colors from the GretagMacbeth test chart.

And actually using the tone curves to calibrate colors is quite easy. All that's involved is the following two steps:
  1. Convert the l*a*b* color values for the GretagMacBeth patches to RGB in the color space of the program in question
  2. Use the tone curve to adjust the RGB values in accordance with the curve
Once we've done this, we have RGB values that are what should be displayed for each program, if the color calibration is correct. I've done this for the three programs I'm testing - a spreadsheet with the values is posted here: http://chromasoft.googlepages.com/calibrationspreadsheets.

In the next post in this series, I'll take a look at how each program compares.
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Good news in a difficult year - all the macOS apps that I support - AccuRaw EXR, AccuRaw Monochrome, pcdMagic, CornerFix, dcpTool (both the GUI and command line version), DNG cleaner and pcdtojpeg - now are all available with native Apple Silicon versions for blazing fast performance on Apple's new "M1" processor. Download are in all the usual places.

Enjoy.

There's a whole slew of new camera support, including for Canon's new CR3 format.

Updates of AccuRaw EXR, AccuRaw Monochrome, PhotoRaw are now available on the Apple App Store.

pcdMagic for Windows - the only currently available app that can convert Kodak Photo CD images with correct color and at full resolution - is now available on the Microsoft Windows Store.

This great news for users:

The Windows Store version has a free trial mode that allows the app to be tested without any commitment. The Windows store handles all updates automatically. There's no need to keep track of license codes. The Windows store only supports the latest versions of Windows 10.
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As usual when new Leica cameras come out, I took a quick look inside a DNG from one of Leica's new Leica CL  cameras:

The camera name shows as "LEICA CL" The image data is 14-bit. There is no compression used in the DNG I looked at.  The DNG version is 1.4, with a "backward version" of 1.3. There is a reason for this - DNG 1.3 allows for opcodes, which Leica use for lens correction.
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So finally, after many years of searching, I have an answer to the question that torments all who go down the digital color rabbit hole.

This is from XKCD, brought to my attention via an article on the Digital Transitions website about the Phase One IQ3 100mp Trichromatic.

Back in January, when the new Leica M10 was introduced, there were claims that the improvement in dynamic range from the Leica M240 to the M10 was of the order of 1.5 to 2 stops.  At the time, I wrote that just by eyeballing the published images, I believed the improvement to be "closer to 0.5 stops than 1.5-2".

Much to my surprise, given what I had thought to be just a basic explanation of why dynamic range is a tricky concept, the post generated a lot of push-back. And I mean a LOT.

dcpTool has been available for quite a while as a command line application for Windows and the Mac. But now it available in the form of an easy to use Mac app, with powerful batch processing capabilities. dcpTool for the Mac is available from the App Store.

dcpTool allows you to:

Decompile DNG Camera Profile (DCP) files in XML. The XML can then be read and edited with a simple text editor. Recompile edited XML into DCP files Remove "Hue twists" from camera profiles.
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Many cameras embed lens corrections into raw the raw files that they produce. Generally, that's a good thing - straight lines stay straight, etc. For an example of lens corrections in practice, take a look at this post about the Leica SL.

But, as the saying goes, "there is no free lunch". Lens corrections also have some downsides:

Lens corrections result in a small reduction in sharpness.

Those of you that have read the Leica M10 raw file analysis post will know that M10 DNGs have more baggage in them that is typically the case for a Leica DNG. I've put together a little app to clean them up, called DNG Cleaner (Mac only for the moment).

AccuRaw users might have gotten a bit of a surprise recently - AccuRaw has turned into AccuRaw EXR, and is now at version 3.

The reason for the name change is that the focus of the AccuRaw product has changed a bit, based on what users were actually doing with it. AccuRaw has always been focussed on having highly linear color response, with no "hue twists" or other surprises in the color rendering.
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