Joseph Holmes

• Natural Light Photography

About My Master Working Spaces and Chroma Variant Sets in Detail

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August 16, 2006 (Revised March 7, 2017)

Summary:

First, I have my original pair of profiles built for scans of transparencies (aka chromes), each with the same gamut, but different tone curves. Second, I have a newer quintet of profiles built specifically for use with digital cameras, all sharing the proprietary, perceptually linear tone curve of the Chrome Space 100 transparency profile, in a useful and very carefully crafted progression of gamut volumes. The middle one of the quintet, DCam 3, is also particularly well-suited for scans of color negatives. Lastly, I've added a Monochrome working space profile which shares the same tone curve (a zero gamut "space") which can be a nice complement to my DCam spaces and Chrome Space 100 when doing B&W printing, on account of its sharing the same tone curve. I include it now in all of the sets with master spaces which share its tone curve. Its same function is best met by Adobe's Gray Gamma 1.8 and 2.2 profiles when using master spaces with those tone curves, including Pro Photo and Adobe RGB, respectively. These are my master spaces:

DCam 1, J Holmes 
DCam 2, J Holmes 
DCam 3, J Holmes 
DCam 4, J Holmes 
DCam 5, J Holmes 
Chrome Space 100, J Holmes 
Ekta Space PS 5, J Holmes
Monochrome, J Holmes

I also have sets of 29 Chroma Variants for each of my seven color working spaces, plus sets for Adobe® RGB (1998) and ProPhoto RGB — nine chroma variant sets in all. If the last thing you need in your life is more bewildering choices to do with your computer, check out my FAQs and Tips page, which also contains advice on choosing sets and has answers to a number of relevant questions.

Profiles and Sets:

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(Compare master profile gamut volumes here — 64KB JPEG)

(Find many more gamut diagrams in Sections I, II and IV of this page.)

(Compare the five DCam master profile gamut volumes here.)

1) DCam 1, J Holmes set: The first of my five new spaces designed in 2006 specifically for use with digital cameras, by far the smallest, and intended solely for images without very saturated colors and with relatively neutral highlights and shadows. Here is an example. This space is intended as a special-purpose supplement to the other spaces for getting the finest precision from relatively muted images. Light colors of modest saturation are likely to be clipped, but this space offers the possibility of taking extra good care of low-gamut images that might otherwise wind up occupying a tiny fraction of the volume of the working space, by keeping image quantization to a very low level. It has a gamut volume nearly 11 percent smaller than sRGB and over 38% smaller than Adobe 1998. It is exactly half the volume of DCam 2. It covers a minimal color range but it is carefully balanced around the core colors of digital capture. Its headroom is too low for most images with moderately colorful lighter tones to avoid clipping entirely. It is the space I use the third most often, after DCam 2 and DCam 3, respectively.

gamut diagram

Chroma Variant Set — 29 variants: +04, +08, +12, +16, +20, +25, +31, +37, +44, +52, +60, +70, +80, +90, +99, -04, -08, -12, -18, -24, -30, -37, -44, -52, -60, -70, -80, -90, -99 plus the Master space and the Monochrome space

2) DCam 2, J Holmes set: With fully double the volume of DCam 1, this is the second of my five new spaces designed in 2006 specifically for use with digital cameras. DCam 2 is the space I use most often and together with DCam 1 and 3 makes a great all-around set. It has a gamut volume 23 percent larger than Adobe 1998 and about 79% larger than sRGB, plus it is much more efficiently shaped than Adobe 1998 for containing likely actual image colors. I estimate that it contains about 50% more of the most useful subject color volume than Adobe 1998 does. It can contain all the colors that we can see on nearly all displays available today, except for a few of their very strongest blues, and a great deal more besides.

I advise using Adobe 1998 as the color space for in-camera JPEGs, so long as it and sRGB remain the only two choices. When you are only concerned with the RAW captures from your camera (and not JPEGs), setting the camera to sRGB may help to make the blinking highlight warning more sensitive to blown colorful highlights.

gamut diagram

3) DCam 3, J Holmes set: The third of my five new spaces specifically for digital cameras, DCam 3 is a more spacious and forgiving, general-purpose, very large gamut space for digital camera captures. This space is 133% larger in volume than sRGB, 61% larger than Adobe RGB, 30% larger than DCam 2, and 20% larger than Chrome Space 100. Perhaps most importantly it is 24% smaller than ProPhoto RGB, yet it covers essentially the same percentage of significant colors. It very efficiently covers the range of colors likely to be captured by a digital camera, with substantially more green to red range, meaning especially more yellow and nearby yellow-green and orange, than Chrome Space 100 and somewhat fewer purple-blues. This is the best all-around space I know of for digital capture. It's also theoretically ideal, therefore, to be a good fit for the likely range of all colors which you might capture with color negatives (convert to DCam 3 from the scanner profile that you use for color negs).

gamut diagram

4) DCam 4, J Holmes set: The fourth of my five new spaces specifically for digital capture and the second largest of the five, DCam 4 is a general-purpose, extremely large gamut space for digital camera captures, with a gamut volume and shape similar to that of Kodak's ProPhoto RGB, but like most of my spaces it uses my proprietary tone curve for better perceptual linearity and therefore better-protected output quality on ideal printers, and it is a bit more efficiently shaped than ProPhoto in my opinion. This space is 204% larger than sRGB, 110% bigger than Adobe RGB, 70% larger than DCam 2, 56% bigger than Chrome Space 100, and 31% bigger than DCam 3. This space, like ProPhoto, should generally only be employed with 16-bit per channel image data, given its great size, however these should not be considered hard and fast rules. It is a viable choice for a single space for all digital captures to the same extent that ProPhoto is. If you are comfortable with ProPhoto's very large size, then this is a somewhat better alternative, with a better tone curve, especially when combined with its matching variant set. Note that I am offering a variant set for ProPhoto as well, which may be preferable if you are stuck with a RAW converter which won't let you choose any working space to convert into (though most now do allow you your choice of output spaces, including Lightroom and ACR), or if you already have work in progress with ProPhoto, i.e. with image adjustment layers, for example. It's best to get into the correct master space prior to creating adjustment layers because changing the tone curve of the working space when converting between spaces with different TRCs will change the layers' effects.

gamut diagram

5) DCam 5, J Holmes set: The fifth and largest of my five new spaces specifically for digital capture, DCam 5 is useful as a special-purpose, extremely large gamut space for digital camera captures and other RGB imaging work. It has a gamut volume and shape just sufficient to perfectly encompass the entire human visual gamut. Like most of my spaces it uses my proprietary tone curve for optimal perceptual linearity. The net, Lab-constricted gamut volume of this space is 324% larger than DCam 1, 278% larger than sRGB, 161% bigger than Adobe RGB, 112% larger than DCam 2, 95% bigger than Chrome Space 100, 63% bigger than DCam 3, and 25% bigger than DCam 4. Its non-Lab-constricted gamut is about 8% larger still. This space, like DCam 4 and ProPhoto, should generally only be employed with 16-bit per channel image data, given its great size. DCam 5 provides a lot more headroom than DCam 4, though this range of added headroom is sparsely populated by typical image colors, so under most circumstances it should not be particularly useful. It may prove useful, however, as a space into which to do batch RAW conversion, so as to defer the handling of clipping issues until later on. After years of looking at the way RGB spaces are limited in their ability to cover the CIE chromaticity diagram's visual gamut range by the inability of the blue coordinate to be placed below the x-axis, I just decided that I wanted to make such a profile, and the exact coordinates necessary to just fully encompass the visual gamut were the most obvious and appealing design for such a giant space. Perhaps others will find uses for it which have not occurred to me. It is available without chroma variants as part of the Eight Master Spaces set, which goes for $30.

gamut diagram

6) Chroma Variant Set #6 [for use with Adobe® RGB (1998)]†: A new and very handy option for controlling color better with images that are already in Adobe RGB.

gamut diagram

Set of 29 variants: +04, +08, +12, +16, +20, +25, +31, +37, +44, +52, +60, +70, +80, +90, +99, -04, -08, -12, -18, -24, -30, -37, -44, -52, -60, -70, -80, -90, -99

7) Chroma Variant Set #7 (for use with ProPhoto RGB)†: A new and very handy option for controlling color better with images that are already in Kodak's ProPhoto RGB (aka ROMM RGB, aka RGB Master). This is also an economical, all-purpose complete set for images that will remain in 48-bit form at least until converted into an output space.

gamut diagram

Set of 29 variants: +04, +08, +12, +16, +20, +25, +31, +37, +44, +52, +60, +70, +80, +90, +99, -04, -08, -12, -18, -24, -30, -37, -44, -52, -60, -70, -80, -90, -99

8) Chrome Space 100, J Holmes: this is an overhauled version of my first working space, Ektachrome Space, J Holmes and replaces it, as of mid-2005. Chrome Space 100 is backward compatible with the original space and cleans up a few technical issues that I was unable to address when I first created my master archiving space for scanned film. I have used Ektachrome Space for all my scanning from 1997 through 2005, and Chrome Space 100 from then on. The newer version can be assigned to files scanned into the older version with essentially no visible change. The gamuts and white points of Chrome Space 100 and its sister space Ekta Space PS 5, J Holmes (aka Ekta Space) are identical. Only the tone curves are different. Chrome Space 100 uses a custom 1,024-point tone curve very carefully designed to match the tonality of perceptually linear printers. This curve is shared by my DCam spaces. Ekta Space instead uses a simple Gamma 2.2 curve, as do Adobe RGB and some other spaces (most working spaces use gamma curves). Gamma curves are too flat near black. I built Ekta Space because Adobe® Photoshop® 5 did not support RGB spaces unless they had simple gamma curves, but Ekta Space went on to become the more commonly used of the two because I gave it away from the beginning. My transparency spaces were conceived around the actual gamut of the dyes in transparency films, as mapped by a proper scanner profile, so they are most appropriate for use with scans of positive films, however as a practical matter they work well with scans of color negatives and fairly well with digital camera captures, though weak on the yellow side.

Note that the difference between the tone curve of Chrome Space 100 and that of Ekta Space PS 5 below is one that can be very useful to impart extra deep shadow detail to scans that are in Ekta Space by simply assigning Chrome Space 100 or its variants. This is commonly useful with scans of transparencies, which themselves tend to crush shadow detail because the film often has insufficient latitude for the subject matter. Most transparency scans fail to restore as much of this crushed detail as they could and should. Often the scanner profile is inherently bad for shadow detail. Scanning the darkest parts of transparencies is inherently difficult, as the densities are very high, especially most Ektachrome films and Velvia, which each hit 3.8, requiring a scanner with 4.2 capability. Color negatives and especially B&W films are far less demanding in this regard but each of them involves other major challenges. For color negs it's getting the color management right and for B&W negs it's the need for fully diffuse backlight for scanning, even when wet mounting is used, as it should be. Please check out this page to show what happens to an image with dark shadows that is in Ekta Space when you assign Chrome Space 100 to it.

gamut diagram

9) Ekta Space PS 5, J Holmes aka "Ekta Space": download this industry-standard free profile here on the Available Products page. This profile is a variation on my original master working space, Ektachrome Space, J Holmes, which I developed to convert my scans into when I was faced with the need for an optimal RGB space for storing my archive of scanned transparency film, as I began to make fine drum scans of it in 1997. The only difference between it and my original profile is its tone curve, which is a simple gamma 2.2 curve instead of the superior, perceptually uniform tone curve of my original space.

gamut diagram (same as Chrome Space 100)

10) Eight Master Spaces set: No chroma variants, just all of my master spaces. These can be useful in a number of ways, either just as better working space alternatives or as a good way to scope out which chroma variant set(s) to buy.

Set includes: DCam 1, DCam 2, DCam 3, DCam 4, DCam 5, Chrome Space 100, Ekta Space PS5, and Monochrome

† These two sets of chroma variants share no content or information whatsoever from the original profiles, which are the intellectual property of Adobe Systems, Inc. and Eastman Kodak Company, except inasmuch as they utilize the same generic gamma curves and white points as the original profiles. Nevertheless, the chroma variants perfectly complement these spaces just as my other sets perfectly complement my own master profiles. The proprietary tone curve of my profiles is not generic and is therefore protected intellectual property, as is the unique combination of primaries in every published RGB working space. All published profiles are also themselves protected by copyright.

Any and all trademarks referenced in these pages are the properties of their respective owners.

Adobe® Photoshop®, Adobe®, Adobe® RGB and Adobe® RGB (1998) are either registered trademarks or trademarks of Adobe Systems Incorporated in the United States and/or other countries.

(Find many more gamut diagrams in Sections I, II and IV of this page.)

(Jump to Available Products page for pricing or purchase.)