Showing papers presented at "Color Imaging Conference in 1998"

High-Resolution Multi-Spectral Image Archives: A Hybrid Approach

Abstract: We introduce an image capturing system that results in spectral image archives with sufficient spatial resolution and colorimetric accuracy for artwork imaging. In this system, a multi-band, low-spatial resolution multi-spectral image is combined with a high-spatial resolution lightness image (from either a monochrome digital or digitized photograph) to generate a high-spatial resolution spectral image. An alternative way to capture multi-spectral images by combining a trichromatic camera and absorption filters is also presented to overcome the technical problems inherent to the use of interference filters in this kind of imaging.

Overcoming Gamut and Dynamic Range Limitations in Digital Images.

Abstract: The human eye can accommodate luminance in a single view over a range of about 10,000:1 and is capable of distinguishing about 10,000 colors at a given brightness. By comparison, typical CRT displays have a luminance range less than 100:1 and cover about half of the visible color gamut. Despite this difference, most digital image formats are geared to the capabilities of conventional displays, rather than the characteristics of human vision. In this paper, we propose two compact encodings suitable for the transfer, manipulation, and storage of full range color images. The first format is a replacement for conventional RGB images, and encodes color pixels as log luminance values and CIE (u',v') chromaticity coordinates. We have implemented and distributed this encoding as part of the standard TIFF I/O library on the net. The second format is proposed as an adjunct to conventional RGB data, and encodes out-of-gamut (and out-of-range) pixels in a supplemental image, suitable as a layer extension to the Flashpix standard. This data can then be recombined with the original RGB layer to obtain a high dynamic range image covering the full gamut of perceivable colors. Finally, we demonstrate the power and utility of full gamut imagery with example images and applications.

Optimizing color reproduction of natural images

Abstract: The paper elaborates on understanding, measuring and optimizing perceived color quality of natural images. We introduce a model for optimal color reproduction of natural scenes which is based on the assumption that color quality of natural images is constrained by perceived naturalness and colorfulness of these images. To verify the model, a few experiments were carried out where subjects estimated the perceived 'naturalness', 'colorfulness' and 'quality' of images of natural scenes. The judgments were related to statistical parameters of the color point distribution across the images in the CIELUV color space. It was found that the perceptually optimal color reproduction can be derived from this statistic within the framework of our model. We specify naturalness, colorfulness and quality indices, describing the observer's judgments. Finally, an algorithm for optimizing perceived quality of color reproduction of natural scenes is discussed.

Color gamut mapping in a hue-linearized CIELAB color space

Abstract: Color gamut mapping plays a crucial role in color management Depending on the application, it is sometimes desirable to perform color gamut mapping by shifting the lightness and compressing the chroma of an out-of-gamut color while preserving the perceived hue of the color The term Operceived hueO is used to distinguish between the visual sensation of hue and metric hue angle (eg, CIELAB hue angle (hab) ) If a gamut-mapping task constrains CIELAB metric hue angle in the "blue" region of CIELAB, a perceived-hue shift will result Due to these nonlinearities, two hue-linearized versions of the CIELAB color space were generated, one from the Hung and Berns visual data (1995) and one from the Ebner and Fairchild data set (1998) Both data sets consist of visually mapped hue data to planes of constant visual hue These modified versions of the CIELAB color space were psychophysically tested for their hue-linearity characteristics against the CIELAB color space The results of these experiments show that, in the "blue" region of CIELAB, the hue-corrected color spaces are more visually uniform and perform better than CIELAB in gamut mapping situations with respect to perceived hue However, the CIELAB color space performed as good as or better than either hue-corrected spaces outside of the blue region

Combining error diffusion, dithering and over-modulation for smooth multilevel printing

Abstract: A new multitoning technique is proposed that combines error diffusion, blue-noise dithering and over-modulation in an adaptive algorithm to achieve high quality multilevel printing with smooth texture transition. A periodic dither signal is first added to an input digital image wherein the amplitude of the periodic dither signal is a function of the input pixel value for each input pixel. The amplitude of the periodic dither signal is larger for input pixel values near the N output levels, and the amplitude of the periodic dither signal is smaller for input pixel values intermediate to the N output levels to produce a modified input image. Then, a multi-level error diffusion halftoning algorithm is applied to the modified input image wherein the error diffusion halftoning algorithm uses a set of error feedback weights which are adjusted according to the original input pixel value for each input pixel. The sum of the error feedback weights is smaller for input pixel values near the N output levels, and the sum of the error feedback weights is larger for input pixel values intermediate to the N output levels to produce an output multi-level digital image.

Spectral colour prediction model for a transparent fluorescent ink on paper

Abstract: A new spectral colour prediction model for a fluorescent ink printed on paper is presented. It is based on our previous work on transparent support 4 and on a new mathematical formalism which generalizes the Kubelka-Munk theory. The printed paper is modelized by means of three matrices: an interface correction matrix, a matrix exponential modelizing the layer which contains the fluorescent ink, and a reflection matrix caracterising the substrate. The interface correction matrix allows to take multiple reflections into account by operating the Saunderson correction. These matrices are related to physical properties of ink and paper which must be measured: the transmittance spectra, the quantum yields, the absorption bands and the emission spectra of the fluorescent inks, and the reflection properties of the paper. Our new model can predict the reflection spectra of uniform samples for different ink concentrations and under different illuminants. It is applied successfully to predict the spectra of real samples with an average prediction improvement of about in comparison with Beer’s law.

Spectral-Based Ink Selection for Multiple-Ink Printing I. Colorant Estimation of Original Objects

Abstract: Research has been initiated to determine a set of six basis colorants which are the best representation of artwork such as paintings. That is, their spectral information can be accurately reconstructed by linear combinations of the six estimated colorants. Since each painting is possibly created by different colorants, the six estimated colorants are image dependent. The clue leading to the six estimated colorants is the six eigenvectors determined from the corresponding spectral measurements. The relationship between the six eigenvectors and estimated colorants is merely the linear transformation (or geometrical rotation). Based on this faith, a constrained-rotation engine using MATLAB was devised to perform the transformation from the eigenvectors to a set of all-positive vectors as the estimated colorants. Once a set of reasonable colorants is uncovered, this set of colorants can be used to synthesize the original artwork with the least metameric effect between the reproductions and originals.

Gamut Mapping: Evaluation of Chroma Clipping Techniques for Three Destination Gamuts.

Abstract: A psychophysical experiment was carried out to evaluate 5 chroma clipping techniques for gamut mapping. Three different destination gamuts were used in order to determine how the shape of the destination gamut would influence performance of the different mapping techniques. The test images consisted of 7 colored computer-rendered textured spheres and one image which contained all 7 objects. Therefore the effect of hue on the preferred technique could be gauged. Although straight chroma-clipping, keeping lightness constant, was overall the best technique, there were notable exceptions. The results indicate that tradeoffs between global trends and specific exceptions to these trends may need to be implemented based on local gamut shape and object hue in the image.

Gamut Mapping in Munsell Constant Hue Sections.

Abstract: The problem of gamut mapping is of interest in achieving an optimum color reproduction whenever a translation from one device (source) to another device (destination) is requested and the source gamut differs from destination gamut. For printing applications, if the ICC profile specifications are used, gamut mapping is applied to build the color tables that characterize the printing device. Within this approach, the color reproduction performance depends (among other factors) on the ability of the profile to include an efficient mapping method between the device independent color space (referred as the profile connection space, or PCS) and the reproduction device space. In order to map the out of gamut colors to the colors that can be reproduced on an output device, several mapping methods have been proposed. Most of them use a constant angle section in the CIELAB color space [1-6]. Within this section, different strategies can be used according to the reproduction intent. However the constant angle section in the CIELAB space only approximates the constant perceptual hue. Several studies reported perceptual hue shifts along constant angle section in CIELAB [4-6]. This is why, mapping in constant hue angle in CIELAB space may not give satisfactory performances for certain hue values. Figure 1 shows in CIELAB space the perceptual hue shift with the variation of lightness [7]. The oblique lines (i.e. segment (1)-(2)) drawn on the exterior of the hue circle illustrate the hue shift in CIELAB for different lightness levels. The end of the oblique segment closer to the achromatic center of CIELAB section points to the Munsell hue for lightness 2 to 4 (i.e. marked as (1)). The other end of the oblique segment (marked as (2)) points to the same Munsell hue for the lightness 6 to 8. As the segment deviates more from the direction of a hue, the hue shift is larger. For example, the constant hue angle for Munsell 5P hue covers 7 degrees in the CIELAB (a*, b*) plane with the variation of Munsell lightness from 4 to 8. Performing gamut mapping in CIELAB constant angle section can result in perceptual hue error. This error is larger if the mapping procedure modifies the lightness of the mapped color. To overcome the hue shift, we proposed to perform the gamut mapping in a more uniform space. We pick up for this experiment a space that results from re-mapping the CIELAB coordinate system based on the constraints imposed by the Munsell renotation system. In the Munsell renotation system the colors progress from top to bottom

The Creation of the sRGB ICC Profile.

Abstract: This paper describes transforming the sRGB color space standard into an ICC profile. This sRGB ICC profile provides a clear bridge between implicit color management and explicit color management and illustrates the complementary nature of these two approaches. The paper starts by reviewing the current status and content of the sRGB color space standard. It also very briefly reviews the status of the current ICC profile specification. A series of practical considerations are then discussed that were addressed in order to transform a color space standard into an ICC profile. This paper will also discuss several false starts in this transformation and why these efforts were unsuccessful and the consequences to other software and hardware in the market today. This profile was extensively tested and reviewed by a number of companies and this test process is described. A detailed review of the final sRGB ICC profile is provided. Finally, recommendations to other profile builders and the ICC are given in order to make this process more efficient and accurate in the future. Current Status of Specifications SRGB While the ICC provides a robust, flexible, complex color management solution, many markets can be adequately addressed by a well-specified monitor color space. Currently there are a plethora of such formal and informal RGB spaces, including NTSC, PAL, HDTV, NIFRGB, Apple RGB, SGI RGB, and many, many others. Two years ago Hewlett-Packard and Microsoft agreed that each needed a single RGB space ubiquitous throughout each company. Hewlett-Packard in particular has a long history of internal color standards including PCL and ColorSmart. After some negotiation, both companies agreed to collaborate on this effort. Hewlett-Packard and Microsoft developed and began to propose the addition of support for a standard color space, sRGB, within Microsoft products (including operating systems), HP products and the World Wide Web. During the last three years Hewlett-Packard, Microsoft and many other premiere imaging companies and individual color experts have been actively refining and supporting the progress of this proposal through a formal international standardization process. The current status of the draft standard is a committee draft for vote stage (CDV) in the IEC TC100 61966 Project Team. 1 This is equivalent to the formal draft international standard (FDIS) stage in ISO terminology. It is hoped that the final international standard will be formally published in early 1999. The aim of this color space is to complement the current color management strategies, particularly ICC, by nabling a simple method of handling color in operating systems and the World Wide Web. This method utilizes a simple and robust color space definition that will provide good quality with minimum transmission and system overhead. Current Status of ICC Specification The purpose of the ICC is clearly stated in its specification. "The International Color Consortium was established in 1993 by eight industry vendors for the purpose of creating, promoting and encouraging the standardization and evolution of an open, vendor-neutral, cross-platform color management system architecture and components." 2 These vendors represented the major platform vendors interested in color management (Apple, Adobe, Microsoft, Silicon Graphics, Sun and Taligent) and two active color management vendors interested in open standards (Agfa and Eastman Kodak). The German graphic arts institute, FOGRA, was an honorary founding member. This honor acknowledges the critical role FOGRA played on initiating these activities. The major effort to date has been the creation of the ICC profile format. The intent of the ICC profile format specification is "to provide a cross-platform device profile format. Such device profiles can be used to translate color data created on one device into another device's native color space. The acceptance of this format by operating system vendors allows end users to transparently move profiles and images with embedded profiles between different operating systems. For example, this allows a printer manufacturer to create a single profile for multiple operating systems. " During the last three years, the ICC has made little progress in formal standardization. Several ICC working groups are active in this area, including a reference implementation working group. If these working groups are successful and their results are adopted by the general ICC membership, it appears that the ICC could be ready to propose its profile format specification as a formal standard within the next 24 months. Complementary Nature of sRGB and ICC A clear, complementary usage path between sRGB and ICC color management is a priority. Microsoft and HP are publishing a free "golden standard" sRGB ICC profile to help integrate ICC and sRGB within a single color management system. Both companies believe that there are some situations where embedding an ICC profile, even an abbreviated profile, is not practical. Both companies strongly support ICC and are not only implementing products supporting ICC, but are actively working within the ICC to resolve the technical problems described below. Both companies also believe that there are many situations where sRGB is an inappropriate solution. In summary, sRGB provides a simple and broadly applicable, but inflexible color management solution and the ICC provides a robust, flexible color management solution, but with significant overhead. Table 1 illustrates the guidelines for use of sRGB. It provides a clear model of what ICC profile is used depending on whether ICC profiles are available or not. This model clearly illustrates the complementary nature of sRGB and ICC color management solutions. Table 1: sRGB ICC Profile Usage in Color Management ICC/ sRGB ICC Source Profile No ICC Source Profile ICC Destination Profile ICC Source ICC Destination sRGB Source ICC Destination No ICC Destination Profile ICC Source sRGB Destination sRGB Source sRGB Destination Building the Profile Practical Considerations The sRGB profile is designed for many different devices including printers, monitors and scanners. It is a generic profile that works well with all of these devices. The profile will be embedded in many images and used for web publication, so it is as small as practical. The sRGB profile includes information for future compatibility with potential ICC changes and is compatible with the latest CIE recommendations. The profile is compatible with existing color management modules (CMM's) and contains no private tags. False Starts and Blind Alleys The ICC profile specification clearly defines how to arrange the bits to create an ICC profile. Originally, it was considered a trivial task to follow the specification and create an sRGB profile. A project to evaluate and test a proposed standard sRGB profile was initiated. This soon became a project to create a profile because of the problems iscovered with the test profile. Several attempts to build a better profile failed. These attempts are described to prevent others from rediscovering the same issues and to explain the ICC fixes needed. A Monitor Profile Implemented with 3D LUTs The first profile under test was a look-up table (LUT) based input profile with a three dimensional (3D) LUT defining the color transform from Lab to sRGB. This profile was created with a tool that included a gamut compression algorithm. This caused unacceptable results because the transforms were not reversible. Transforming colors with a red, green, or blue value near the lower or upper limit of 0 or 255 produced significant errors with all CMMs tested. The yellow (255,255,0) transform added enough cyan to cause visible and annoying cyan dots on ink jet printers. Multiple passes of an image through color management degraded the colors further. Significant differences in the neutral axis were also observed when using this profile with different CMMs. XYZ Profile Connection Space The Lab profile connection space (PCS) requires a nonlinear transform to and from sRGB. The XYZ PCS allows a linear transform to be defined if the non-linear gamma adjustment is not included. This transform can be defined as a 3x3 matrix multiply operation. The 3D LUT based profiles have a provision for the definition of a 3x3 matrix for this purpose. The ICC specification clearly defines the order of the data processing of the elements of the tag structure as: (matrix) -> (1d input tables) -> (multidimensional lookup table) -> (1d output tables). This is the correct order of operations for transforms from the PCS to device space for RGB monitors. Unfortunately, the processing order is the same for transforms back into the PCS, making the 3x3 matrix useless in this direction. To create a 3x3 matrix multiply operation without an interpolating look up table, a matrix based input profile must be used. This type of profile produces accurate and reversible color conversions with all CMMs tested. Unfortunately, most color management implementations do not allow an input profile to be associated with an output device such as an sRGB printer. This problem requires the ICC to provide a working matrix based solution for printers. This could be solved by extending the monitor matrix based structure for RGB printers, and/or fixing the matrix processing order of the look-up table based structure. Backward Compatibility The sRGB profile is expected to be backward compatible with existing color management systems. Although the ICC profile specification provides details on the structure of the file, many technical details and other practical information is missing. The white point tag is especially confusing. The ICC is aware of the confusing language in this definition. 3 Interpreting the text literally seemed to indicate that the white point value should be D50 to match the profile connection space. However, since the D50 white point of the PCS is inclu

Multiscale Model of Adaptation, Spatial Vision and Color Appearance.

Abstract: In this paper we present a multiscale color appearance model which simulates luminance, pattern and color processing of the human visual system to accurately predict the color appearance attributes of spectral stimuli in complex surroundings under a wide range of illumination and viewing conditions.

Resiliency of the Multiscale Retinex Image Enhancement Algorithm

Abstract: The multiscale retinex with color restoration (MSRCR) continues to prove itself in extensive testing to be very versatile automatic image enhancement algorithm that simultaneously provides dynamic range compression, color constancy, and color rendition, However, issues remain with regard to the resiliency of the MSRCR to different image sources and arbitrary image manipulations which may have been applied prior to retinex processing. In this paper we define these areas of concern, provide experimental results, and, examine the effects of commonly occurring image manipulation on retinex performance. In virtually all cases the MSRCR is highly resilient to the effects of both the image source variations and commonly encountered prior image-processing. Significant artifacts are primarily observed for the case of selective color channel clipping in large dark zones in a image. These issues are of concerning the processing of digital image archives and other applications where there is neither control over the image acquisition process, nor knowledge about any processing done on th data beforehand.

Colorant Selection for Six-Color Lithographic Printing.

Abstract: Two criteria for selecting ink sets for six-color lithographic printing are discussed. The first is the volume, in CIELAB space, of an approximation of the gamut. The second is the number of pixels within a digital image (or images) whose colors are contained within the approximate gamut. In order to obtain a balance between accuracy and efficiency, the different steps in the process are prioritized according to their impact on accuracy, their requirements for specialized measurements, and the computational load they create. Factors which have a first-order impact on accuracy are measured, while factors with higher-order, less controlling, impact are computed or estimated. Overprints of two or more colorants are estimated using a spectral model, rather than measured from printed samples. Combinations of inks on the gamut surface which contain intermediate amounts of inks are estimated using a spectrally-sharpened wideband model. The estimation is performed in a space in which subtractive colorants behave more linearly than density. A convex hull of the gamut is constructed in the linear space, using Computer Graphics routines. Through repeated bisection, the surface of the gamut is sampled in the linear space. The coordinates of the vertices are then transformed into CIELAB color space, for display, comparison, and analysis.

DjVu: a Compression Method for Distributing Scanned Documents in Color over the Internet.

Abstract: We present a new image compression technique called “DjVu” that is specifically geared towards the compression of scanned documents in color at high revolution. DjVu enable any screen connected to the Internet to access and display images of scanned pages while faithfully reproducing the font, color, drawings, pictures, and paper texture. With DjVu, a typical magazine page in color at 300dpi can be compressed down to between 40 to 60 KB, approximately 5 to 10 times better than JPEG for a similar level of subjective quality. A real-time, memory efficient version of the decoder is available as a plug-in for popular web browsers.

Experiments in Sensor Sharpening for Color Constancy.

Abstract: Sensor sharpening has been proposed as a method for improving color constancy algorithms but it has not been tested in the context of real color constancy algorithms. In this paper we test sensor sharpening as a method for improving color constancy algorithms in the case of three different cameras, the human cone sensitivity estimates, and the XYZ response curves. We find that when the sensors are already relatively sharp, sensor sharpening does not offer much improvement and can have a detrimental effect. However, when the sensors are less sharp, sharpening can have a substantive positive effect. The degree of improvement is heavily dependent on the particular color constancy algorithm. Thus we conclude that using sensor sharpening for improving color constancy can offer a significant benefit, but its use needs to be evaluated with respect to both the sensors and the algorithm.

Prime colors and color imaging.

Abstract: In modeling color vision, certain visible wavelengths have special significance. A growing body of scientific work shows that the wavelengths around 450nm, 540nm and 605nm, the so called prime-color (PC) wavelengths, are fundamental to color vision. Perhaps unsurprisingly, these same wavelengths are often discussed in the color imaging literature. Monitors that can display a large gamut of colors and are visually efficient have phosphor-primary peaks at the PC wavelengths. Color cameras that have peak sensitivities at the PC wavelengths have favorable color-balancing properties. Why are the PC wavelengths so important? This paper provides a start toward a mathematical theory to answer this question.

Image Noise and Colorimetric Precision in Multispectral Image Capture.

Abstract: The performance of a multispectral (more than three color-records) camera is addressed from the standpoint of pixel-to-pixel error introduced by image detection. Matrix equations are given for the propagation of this image noise from camera signal through colorimetric transformations. Results of the analysis are shown to agree with experimental results, allowing the prediction of system colorimetric precision.

Computer synthesis of spectroradiometric images for color imaging systems analysis

Abstract: A technique to perform full spectral based color calculations through an extension of OpenGL has been created. This method of color computations is more accurate than the standard RGB model that most computer graphics algorithms utilize. By maintaining full wavelength information in color calculations, it is also possible to interactively simulate and display many important color phenomena such as metamerism and fluorescence. This technique is not limited to creating simple images suitable for interactive display, however. Using this extension, it is also possible to synthesize spectroradiometric images of arbitrary spatial and spectral resolution, for use in color imaging system analysis.

NIST Reference Spectroradiometer for Color Display Calibrations.

Abstract: A program to develop calibration services for colormeasuring instruments has been established recently at the National Institute of Standards and Technology (NIST) to address commercial and industrial needs for higher-accuracy measurements of displays. In particular, a reference spectroradiometer has been built with the goal of enabling measurements of displays with the smallest possible uncertainty. The instrument has been characterized for wavelength error, variable bandpass, stray light, linearity and random noise. The accuracy of color measurements with this instrument has been assessed using detailed simulations incorporating the measured performance characteristics of the instrument. In the simulations, the uncertainty in color measurements of sixteen CRT and LCD display colors was calculated. The results of the simulations imply that the instrument is capable of measuring colors of displays with a combined standard uncertainty of approximately 0.001 in chromaticity (x,y) and 1 % in luminance (Y ).

Goniospectral Imaging of 3D Objects.

Abstract: A multiband imaging system with multi-angle illumination and a processing algorithm for multiband images acquired by the system are presented for extracting goniospectral information of 3D objects. Based on a dichromatic reflection model, multiband images are separated into diffuse and specular components. Then, the model parameters are determined pixelwise and archived. Using these parameters, an image of the 3D object under an arbitrary spectral and spatial distribution of illuminant can be predicted and displayed. A fundamental experiment to confirm the principle of this method is presented.

Standard High Precision Pictures : SHIPP

Abstract: Along with the recent rapid penetration of personal computer, internet, digital camera, etc., full color images have become widely handled in digital form by various classes of users. In such a trend, technologies for color management system (CMS), printing, hardcopy output, image transmission, image compression, etc. are highlighted, and their refinements are on way to achieve higher image qualities. In the research activities in image technologies, the significance of high precision standard pictures is self-evident as they facilitate the evaluation of image processing algorithm, the accurate comparison of image output devices, etc. In April 1997, the activity of the Committee for Standard High Precision Pictures (Note 1) has resulted in the preparation of high resolution standard pictures characterized by that they are expressed by 16-bit XYZ data as well as 8-bit CIELAB data and Calibrated RGB data. The set of pictures named SHIPP consists of four full color natural scenes and a computer-generated chart, each expressed in three color spaces, i.e., XYZ, CIELAB, and Calibrated RGB. A detailed description of the last color space will be given later. The image data are formated ac cording to TIFF6.0 and recorded in a CD-ROM. Objectives and Background An example of standard color image data is given by ISO/ JIS-SCID (Standard Color Image Data (Note 2)). This is the first standard in the form of digital data commonly applicable to any output devices, and is now widely used in the technical fields of printing, hardcopy, image transmission and compression, etc. However, there are a few problems with SCID. Since it originated in the commercial printing industries, its image data is described in terms of the dot coverages in CMYK, which makes it difficult to accurately define colors when the data are to be used in image media other than conventional printing. Moreover, the data depth is limited to 8-bits/channel, thus sometimes causing noticeable quantization errors during various types of image processing. In order to solve these problems, the Committee for Standard High Precision Pictures started its activity to prepare a set of standard pictures with the following characteristics: 1). Device-independent XYZ/CIELAB values, 2). Image data of 2-bytes/channel, and 3). Image resolution of 4096 × 3072. The activity resulted in the development of a set of full color pictures named SHIPP satisfying the above aims in April 1997. SHIPP is expected to meet well the today’s requirements in the various technical fields such as the color gamut evaluation of imaging systems, the image quality evaluation of image output devices, the estimation of the degree of quality deterioration accompanied by image data compression, etc. Full Color Natural Scenes and Color Chart Comprising SHIPP Table 1 depicts the specifications of the image data for full color natural scenes and for the color chart composing SHIPP. In choosing these scenes, the 8 scenes of SCID were referred to from the viewpoint of significant attributes for Table 1. Specifications of SHIPP No. Nickname Pixels Color Space Data Volume Main Subjects Evaluation Objects (width × height) (mbytes) XYZ 75.5 Tone reproduction P1 Bride 3072 × 4096 CIELAB/ 37.7 Close-up portrait of flesh Calibrated RGB XYZ 75.5 Fine, regular Image processing P2 Harbor 4096 × 3072 CIELAB/ 37.7 structures technique Calibrated RGB XYZ 75.5 Highly saturated Color P3 Wool 4096 × 3072 CIELAB/ 37.7 colored products reproduction Calibrated RGB XYZ 75.5 Lustrous metal Reproduction P4 Bottles 3072 × 4096 CIELAB/ 37.7 products of gray Calibrated RGB XYZ 21.8 Color C1 Chart 2736 × 1332 CIELAB/ 10.9 Color patches reproduction Calibrated RGB