Bowen, A W

Oulton, David

Peterman, E

English

An investigation into Colorimetrically calibrated colour imaging systems is reported which enable the analysis of the effect of texture on colour appearance

The University of Manchester - Institutional Repository

The University of Manchester ResearchColour Systems for the Analysis and Definition of SurfaceTexture, and its Effect on Colour AppearanceDocument VersionAccepted author manuscriptLink to publication record in Manchester Research ExplorerCitation for published version (APA):Oulton, D., Peterman, E., & Bowen, A. W. (1998). Colour Systems for the Analysis and Definition of SurfaceTexture, and its Effect on Colour Appearance. 65-75. Paper presented at 5th International Conference Colour andColorimetry, Slovenia.Citing this paperPlease note that where the full-text provided on Manchester Research Explorer is the Author Accepted Manuscriptor Proof version this may differ from the final Published version. If citing, it is advised that you check and use thepublisher's definitive version.General rightsCopyright and moral rights for the publications made accessible in the Research Explorer are retained by theauthors and/or other copyright owners and it is a condition of accessing publications that users recognise andabide by the legal requirements associated with these rights.Takedown policyIf you believe that this document breaches copyright please refer to the University of Manchester’s TakedownProcedures [http://man.ac.uk/04Y6Bo] or contact uml.scholarlycommunications@manchester.ac.uk providingrelevant details, so we can investigate your claim.Download date:08. Jun. 2022Quantifying the effect of Texture  on Colour Appearance David P.Oulton, Elise Peterman  & Andrew W. Bowen Dept of Textiles UMIST 1998 Texture Rich Photo-Realistic Images Contain :- • The Micro-Level Colour Differences which represent Texture. • Spatially distributed objects and object components. A Photo-realistic Image A Different Type of Image Texture Rich Imaging Systems • CIE Co-ordinate defined point-colour. • The Micro-Level Colour Differences which represent Texture. • The Contents of a Photo-Realistic Image. • CIE Co-ordinate based Image Storage and Analysis Strategies. Image Analysis • Logical Objects within Images have clearly defined easily separated Colour-Sets. • The Key Discriminating Variable is Hue. • Automatic Object Differentiation has proved to be highly effective, based on Delta H, Delta C and Delta L, using controlled band-widths. Colour-Set membership in a Vector Space Each of several thousand colour definitions is represented, as a set of n pixels, at a distance H,C,L from the base-colour.  Point Colours Form a Variable Density Cloud, round the base-colour definition. L C H Base (Intrinsic) Colour Set of Pixels Intrinsic Colour and Colour Appearance • Intrinsic colour is defined as a central property of the colorants present (product colour specification). • Colour Appearance is produced by applying the intrinsic colour to a given substrate. Intrinsic Colour Measured Colour (texture 1) Measured Colour (texture 2) MVD2 MVD1 Base Colour Object Colour-Set Base Colour Object Colour-Set Measures of Texture Appearance MCI (Mean Colour Identity) reduces to a single colour identity the combined effects of an array of point-colour specifications.  MDD values express, for each dimension of colour difference, whether the texture appears lighter, darker, brighter, duller etc. than expected. They register and define single dimensional displacements or deviations from some intrinsic colour definition. An MVD value expresses the vector displacement in three dimensions of colour-space that links intrinsic colour to colour appearance. The intrinsic colour from which the MVD is calculated may be a measured colour specification, or be derived by visual matching.  Colour appearance variation MDDL from winding Tuft  =  -27.4, Knit  =  -11.8 Deriving a value for Texture colour appearance A single CIE colour specification (the MCI value) is   calculated from many pixel colour specifications. The pixel colour specifications come from a visually and numerically correct image of the texture. A visually and / or numerically correct colour appearance is derived from a -    Colour measurement (if the sample can be measured)       A visual matching          Calibration using a measured image-colour ‘hitching post’.     Measuring MCI, MDD and MVD values MDD and MVD values represent the displacement in        CIEL*a*b* colour-space of a texture relative to the      reference intrinsic colour. They are measured by comparing the MCI values of two    textures, which are derived from image content. They are characteristic of a given texture, and are constant across large volumes of colour-space. Validation using Imaged Textures Observer trial validation was used to test for constant MVD with constant texture. 63 individual yarn winding samples widely distributed in colour-space have been shown to have an MVD of Zero to a common reference winding [EPSRC Final Report]. 60 samples were made in three different textures, each texture was fabricated from a single yarn, using 20 different colours. The results are examined further in this account. Yarn winding test colours Orientation  Effects         V ariat ion o f  Light ness wit h Text ure0204060R1 Y1 G1 C1 V1Samples grouped by hue Lightness valueWindTuftKnitVariation of Chroma with Texture0204060R1 Y1 G1 C1 V1Samples grouped by hueChroma valueWindTuftKnitResults for samples with intrinsically low lightness and low chroma   MDDc is negative for tufts         Variation of Lightness with Texture050100R2 Y2 G2 C2 V2Samples grouped by hueLightness valueWindTuftKnitVariation of Chroma with Texture0204060R2 Y2 G2 C2 V2Samples grouped by hueChroma valueWindTuftKnitResults for samples with intrinsically high lightness and low chroma   MDDc is now positive for tufts         Va r i a t i on of  Li ght ne ss wi t h Te x t ur e050100R3 Y3 G3 C3 V3Samples grouped by hueLightness valueWindTuftKnitVariation of Chroma with Texture020406080R3 Y3 G3 C3 V3Samples grouped by hueChroma valueWindTuftKnitResults for samples with intrinsically low lightness and high chroma   MDDc is again negative for tufts         Variation of Lightness with Texture0501 00R4 Y4 G4 C4 V4Samples grouped by hueLightness valueWindTuftKnitVariation of Chroma with Texture020406080R4 Y4 G4 C4 V4Samples grouped by hueChroma value WindTuftKnitResults for samples with intrinsically high lightness and high chroma   MDDc now has increased positive value for tufts compared to low lightness samples  Overall derived and measured MDD values Values derived from visually matched images TEXTURE TYPE MDDL MDDC MDDh  Tufts                -19.56 -1.15 1.88  Knits  -11.06 -2.82 -2.45  Values derived from spectrophotometric measurements TEXTURE TYPE MDDL MDDC MDDh  Tufts  -15.0  -2.45 1.18   Knits  -3.54 -1.70  -1.09    Individual variations with lightness and chroma MDD Trends from reference texture  for individual lightness and chroma groups.           TEXTURE      MDD values for samples with Low Chroma           Low lightness        High Lightness   MDDL MDDC MDDh MDDL MDDC MDDh   Tufts -17.25 -5.00 1.12 -13.83 3.32 2.20   Knits -10.43 -3.20 -2.32 -17.43 -3.82 -0.64     MDD values for samples with High Chroma                   Low lightness             High Lightness    MDDL MDDC MDDh MDDL MDDC MDDh   Tufts -15.12 -10.35 1.34 -24.89 9.18 1.96   Knits -5.56 -3.86 -1.94 -13.85 -2.38 -3.84   Conclusions MCI (Mean Colour Identity), MDD (Mean Directional Deviation),  MVD (Mean Vector Deviation or Displacement), and Intrinsic Colour, are introduced as measures of colour appearance change with varying texture. They are shown to relate texture and colour in analyzable ways. A tentative start has been made on image based colour analysis The role of texture in colour appearance may prove to be measurable. 

Colour Systems for the Analysis and Definition of Surface Texture, and its Effect on Colour Appearance

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Colour Systems for the Analysis and Definition of Surface Texture, and its Effect on Colour Appearance

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