Using HDR display technology and color appearance modeling to create display color gamuts that exceed the spectrum locus

Transcription

1 Rochester Institute of Technology RIT Scholar Works Presentations and other scholarship Using HDR display technology and color appearance modeling to create display color gamuts that exceed the spectrum locus Rodney Heckaman Mark Fairchild Follow this and additional works at: Recommended Citation Heckaman, Rodney and Fairchild, Mark, "Using HDR display technology and color appearance modeling to create display color gamuts that exceed the spectrum locus" (2006). Accessed from This Presentation is brought to you for free and open access by RIT Scholar Works. It has been accepted for inclusion in Presentations and other scholarship by an authorized administrator of RIT Scholar Works. For more information, please contact

2 Using HDR Display Technology & Color Appearance Modeling to Create Display Color Gamuts that Exceed the Spectrum Locus Mark D. Fairchild & Rodney L. Heckaman RIT - MCSL High-Dynamic-Range (HDR) Imaging If you had an HDR display, what would you do with it?

3 Measuring Gamuts Lightness/Chroma Boundaries for a Display Technology Lightness The brightness of an area judged relative to the brightness of a similarly illuminated area that appears to be white or highly transmitting. Note. Only related colours exhibit lightness.

4 Chroma Colorfulness, chromaticness, of an area judged as a proportion of the brightness of a similarly illuminated area that appears white or highly transmitting. Importance of White Both lightness and chroma (perceptions) are relative to an area that appears white. Change the white for a constant physical stimulus lightness and chroma change. Can we use this to our advantage in image displays?

5

6

7

8

9 Changing the stimulus that appears white, impacts the appearance of all other stimuli in the scene.

10 Historical Examples Stained Glass Windows, Photographic Transparencies Flare Adjusted Final Goal Real System Computational Question Can we design a display with a perceived color gamut that would exceed the perceived gamut of the spectrum locus on a traditional display?

11 Chromaticity Gamuts! Almost no information on appearance! MacAdam Limits Y/Y n 0.9 y y 0 x x

12 Appearance Gamuts CIECAM02 Lightness - Chroma - Hue Brightness - Colorfulness - Hue Our Procedure Change Diffuse White Point Relative to Display Primary Maxima Compute Affect on Appearance Gamut (CIECAM02)

13 Some Details Typical CRT RGB Primaries Diffuse White Point 100 cd/m2 Primary Max Luminances Increased by Factors of 2 Diffuse White : Black = 100 : 1 Various Surround/Flare Assumptions Computational Procedure Set Viewing Condition Set White Point and Black Point Generate a data set of random display scalars in RGB N = 0 Scale up the maximum luminance of the display Y N,max = 2 N Y 0,max Compute the display s conversion matrix M N based on the scaled up maximum luminance and its chromaticities Compute the set of XYZ s from the data set of RGB scalers and the conversion matrix M N CIECAM02 Compute the set of Lightness, Chroma, Brightness, and Colorfulness from the set of XYZs MATLAB Convex Hull Determine display gamut from data set in Lightness, Chroma, Brightness, and Colorfulness N=N+1 Plot Gamut for each N against the MacAdam Limits

14 Lightness-Chroma Gamuts Red = MacAdam Limits / Spectrum Locus Colorfulness-Brightness Gamuts Red = MacAdam Limits / Spectrum Locus

15 Gamut Summary 11-bits Exceeds Spectrum Locus in Appearance 8-bits below Diffuse White 3-bits above Diffuse White Diffuse White = 100 cd/m 2 Display Max = 800 cd/m 2 Viewing Conditions Effect is Larger in Illuminated Surround Dark Surround - Lower Perceived Contrast Effect of Flare on Gamut Volume Diminishes with Increased Luminance Headroom Details in Forthcoming Color Research & Application Paper

16 Image Examples Image Examples

17 Image Examples Image Examples

18 Image Examples Image Examples

19 The Practicality High-Dynamic-Range Displays Required Becoming Available: e.g. Brightside Technologies New Image Encoding Also Required Homebrewed HDR 3500 cd/m 2 : 0.01 cd/m 2 (350,000:1 Contrast)

20 Measurements of Display Performance Color Appearance Not just Chromaticity Gamuts & Contrast Ratio BUT... How Those are Used... and the Impact of Viewing Conditions CIECAM02 Appears to be an Effective Tool Thank You Rod Heckaman s graduate studies funded by the Macbeth-Engel Fellowship in Color Science