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LibCapy - colorChart

Class to manipulate color charts.

Macros:

#define CAPY_COLORCHART_H

#define CapyColorChartDimDef union { \
  size_t dims[2];                    \
  struct __attribute__((packed)) {   \
    size_t nbRow;                    \
    size_t nbCol;                    \
  };                                 \
}

Definition of ColorChartDim class

Enumerations:

typedef enum CapyColorChartType {
  capyColorChart_QP203,
  capyColorChart_XRiteClassic,
} CapyColorChartType;

Types of color chart

Typedefs:

typedef CapyColorChartDimDef CapyColorChartDim;

ColorChartDim class

typedef struct CapyColorChart CapyColorChart;

Predeclaration of ColorChart class

Struct CapyColorChartDetectOpt :

Struct CapyColorChartDetectOpt's properties:

  double stdDev;

Standard deviation and size of the Gauss kernel

  CapyImgDims_t gaussKernelSize;

  CapyPad(CapyImgDims_t, gaussKernelSize);

  bool flagScoreGradient;

Use the gradient of colors in the scoring function

  CapyPad(bool, flagScoreGradient);

  double thresholdAspectRatio;

Threshold for the aspect ratio of patches

  double thresholdCoverage;

Threshold for the coverage of patches

  double thresholdParallelism;

Threshold for the parallelism of patches

  double thresholdPairing;

Threshold for the pairing of patches

  size_t nbStepDiffusion;

Number of step for score diffusion

  double hysteresis[2];

Thresholds for the hysteresis step in Canny edge detection

  bool flagKeepPairing;

Flag to memorise if we keep pairing after an island of patches has been completed

  CapyPad(bool, 2);

  bool flagKmeansClustering;

Flag to run k-means clustering prior to canny edge detection

  CapyPad(bool, 3);

Struct CapyColorChartDetectOpt's methods:

None.

Struct CapyColorChart :

Struct CapyColorChart's properties:

  CapyColorChartType type;

Type of the chart

  CapyPad(CapyColorChartType, type);

  CapyColorChartDimDef;

Dimensions of the chart

  CapyColorData* colors;

Colors of the chart (ordered as [iRow * nbCol + iCol])

  bool* isInsideSRGBGamut;

Array of flags to memorise which colors are inside the sRGB gamut.

  size_t kernelSize;

Kernel size in pixel to blur the image when extracting the color values (default: 3)

  CapyColorSpace colorSpace;

Color space of the chart

  CapyColorIlluminant illuminant;

Illuminant to interpret the color chart values (default D65)

Struct CapyColorChart's methods:

  void (*destruct)(void);

Destructor

  CapyColorData (*get)(
    size_t const iRow,
    size_t const iCol);

Get the color at a given position in the chart

  CapyQuadrilateral (*locate)(
                    CapyImg const* const img,
    CapyColorChartDetectOpt const* const opt);

Locate a color chart in an image

Input argument(s):

img: the image containing the chart
opt: the detection options

Output and side effect(s):

Return the location of the color chart, clockwise from the top-left corner. Exceptions: May raise CapyExc_NoColorChartInImage if no color chart were located.

  bool (*extract)(
        CapyImg const* const img,
    CapyQuadrilateral const* chartCoord);

Update the color values of the chart with those extracted from the color chart contained in an image

Input argument(s):

img: the image containing the color chart
coords: the four coordinates of the corners of the QP203 in the image, as returned by locate(). If NULL, an automatic localisation of the color chart in the image is performed (to be implemented).

Output and side effect(s):

Return true if the colors could be extracted, else false.

  void (*convertToColorSpace)(CapyColorSpace const colorSpace);

Convert the color chart to another color space

Input argument(s):

colorSpace: the target color space

  void (*matchBrightness)(CapyColorChart const* const refChart);

Correct the color chart to match the brightness of a given color chart

Input argument(s):

refChart: the target color chart

  void (*saveToPath)(char const* const path);

Save the color chart to a path. Format: type, nbRow, nbCol, colors[0].RGBA[0], colors[0].RGBA[1], colors[0].RGBA[2], colors[0].RGBA[3], colors[1].RGBA[0], ...

Input argument(s):

path: the path
Exceptions: May raise CapyExc_StreamOpenError, CapyExc_StreamWriteError

  void (*saveToStream)(CapyStreamIo* const stream);

Save the color chart to a stream (in binary mode). Format: type, nbRow, nbCol, colors[0].RGBA[0], colors[0].RGBA[1], colors[0].RGBA[2], colors[0].RGBA[3], colors[1].RGBA[0], ...

Input argument(s):

stream: the stream
Exceptions: May raise CapyExc_StreamWriteError

  void (*loadFromPath)(char const* const path);

Load the color chart from a path. Format: type, nbRow, nbCol, colors[0].RGBA[0], colors[0].RGBA[1], colors[0].RGBA[2], colors[0].RGBA[3], colors[1].RGBA[0], ...

Input argument(s):

path: the path
Exceptions: May raise CapyExc_StreamOpenError, CapyExc_StreamReadError

  void (*loadFromStream)(CapyStreamIo* const stream);

Load the color chart from a stream (in binary mode). Format: type, nbRow, nbCol, colors[0].RGBA[0], colors[0].RGBA[1], colors[0].RGBA[2], colors[0].RGBA[3], colors[1].RGBA[0], ...

Input argument(s):

stream: the stream
Exceptions: May raise CapyExc_StreamWriteError, CapyExc_MallocFailed

  double (*getSimilarity)(CapyColorChart const* const chart);

Get the degree of similarity of the color chart relative to another chart.

Input argument(s):

chart: the chart to compare to

Output and side effect(s):

Return 1.0 if the two charts are identical. Return 0.0 if the two charts are of different types. Return 1.0 minus the average of Euclidean distances between two same patches in the charts, hence the lower the returned value (possibly negative) the more charts' color differ. If the two charts are in different color space, a copy of 'chart' is converted to the color space of 'that' and used instead.

  CapyImgPos (*getPatchPos)(
    CapyQuadrilateral const* const chartCoord,
                      size_t const iCol,
                      size_t const iRow);

Get the position of the center of a patch in an image given the position of the corners of the color chart.

Input argument(s):

coords: the four coordinates of the corners of the QP203 in the image, as returned by locate().
iCol, iRow: the coordinates of the patch in the chart

Output and side effect(s):

Return the position in the image of the center of the patch

Functions:

CapyColorChart CapyColorChartCreate(
  CapyColorChartType const type,
      CapyColorSpace const colorSpace);

Create a CapyColorChart

Input argument(s):

type: the type of the chart
colorSpace: the color space of the chart

Output and side effect(s):

Return a CapyColorChart

Exception(s):

May raise CapyExc_MallocFailed, CapyExc_UndefinedExecution.

CapyColorChart* CapyColorChartAlloc(
  CapyColorChartType const type,
      CapyColorSpace const colorSpace);

Allocate memory for a new CapyColorChart and create it

Input argument(s):

type: the type of the chart
colorSpace: the color space of the chart

Output and side effect(s):

Return a CapyColorChart

Exception(s):

May raise CapyExc_MallocFailed, CapyExc_UndefinedExecution.

CapyColorChart* CapyColorChartClone(CapyColorChart const* const chart);

Clone a CapyColorChart

Input argument(s):

chart: the color chart to clone

Output and side effect(s):

Return a CapyColorChart

Exception(s):

May raise CapyExc_MallocFailed, CapyExc_UndefinedExecution.

void CapyColorChartFree(CapyColorChart** const that);

Free the memory used by a CapyColorChart* and reset '*that' to NULL

Input argument(s):

that: a pointer to the CapyColorChart to free

2022-03-03
in LibCapy,
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