+++ /dev/null
-#ifndef INCLUDED_IMF_RGBA_YCA_H
-#define INCLUDED_IMF_RGBA_YCA_H
-
-//////////////////////////////////////////////////////////////////////////////
-//
-// Copyright (c) 2004, Industrial Light & Magic, a division of Lucasfilm
-// Entertainment Company Ltd. Portions contributed and copyright held by
-// others as indicated. All rights reserved.
-//
-// Redistribution and use in source and binary forms, with or without
-// modification, are permitted provided that the following conditions are
-// met:
-//
-// * Redistributions of source code must retain the above
-// copyright notice, this list of conditions and the following
-// disclaimer.
-//
-// * Redistributions in binary form must reproduce the above
-// copyright notice, this list of conditions and the following
-// disclaimer in the documentation and/or other materials provided with
-// the distribution.
-//
-// * Neither the name of Industrial Light & Magic nor the names of
-// any other contributors to this software may be used to endorse or
-// promote products derived from this software without specific prior
-// written permission.
-//
-// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
-// IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
-// THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
-// PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
-// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
-// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
-// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
-// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
-// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
-// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
-// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-//
-//////////////////////////////////////////////////////////////////////////////
-
-//-----------------------------------------------------------------------------
-//
-// Conversion between RGBA (red, green, blue alpha)
-// and YCA (luminance, subsampled chroma, alpha) data:
-//
-// Luminance, Y, is computed as a weighted sum of R, G, and B:
-//
-// Y = yw.x * R + yw.y * G + yw.z * B
-//
-// Function computeYw() computes a set of RGB-to-Y weights, yw,
-// from a set of primary and white point chromaticities.
-//
-// Chroma, C, consists of two components, RY and BY:
-//
-// RY = (R - Y) / Y
-// BY = (B - Y) / Y
-//
-// For efficiency, the x and y subsampling rates for chroma are
-// hardwired to 2, and the chroma subsampling and reconstruction
-// filters are fixed 27-pixel wide windowed sinc functions.
-//
-// Starting with an image that has RGBA data for all pixels,
-//
-// RGBA RGBA RGBA RGBA ... RGBA RGBA
-// RGBA RGBA RGBA RGBA ... RGBA RGBA
-// RGBA RGBA RGBA RGBA ... RGBA RGBA
-// RGBA RGBA RGBA RGBA ... RGBA RGBA
-// ...
-// RGBA RGBA RGBA RGBA ... RGBA RGBA
-// RGBA RGBA RGBA RGBA ... RGBA RGBA
-//
-// function RGBAtoYCA() converts the pixels to YCA format:
-//
-// YCA YCA YCA YCA ... YCA YCA
-// YCA YCA YCA YCA ... YCA YCA
-// YCA YCA YCA YCA ... YCA YCA
-// YCA YCA YCA YCA ... YCA YCA
-// ...
-// YCA YCA YCA YCA ... YCA YCA
-// YCA YCA YCA YCA ... YCA YCA
-//
-// Next, decimateChomaHoriz() eliminates the chroma values from
-// the odd-numbered pixels in every scan line:
-//
-// YCA YA YCA YA ... YCA YA
-// YCA YA YCA YA ... YCA YA
-// YCA YA YCA YA ... YCA YA
-// YCA YA YCA YA ... YCA YA
-// ...
-// YCA YA YCA YA ... YCA YA
-// YCA YA YCA YA ... YCA YA
-//
-// decimateChromaVert() eliminates all chroma values from the
-// odd-numbered scan lines:
-//
-// YCA YA YCA YA ... YCA YA
-// YA YA YA YA ... YA YA
-// YCA YA YCA YA ... YCA YA
-// YA YA YA YA ... YA YA
-// ...
-// YCA YA YCA YA ... YCA YA
-// YA YA YA YA ... YA YA
-//
-// Finally, roundYCA() reduces the precision of the luminance
-// and chroma values so that the pixel data shrink more when
-// they are saved in a compressed file.
-//
-// The output of roundYCA() can be converted back to a set
-// of RGBA pixel data that is visually very similar to the
-// original RGBA image, by calling reconstructChromaHoriz(),
-// reconstructChromaVert(), YCAtoRGBA(), and finally
-// fixSaturation().
-//
-//-----------------------------------------------------------------------------
-
-#include <ImfRgba.h>
-#include <ImfChromaticities.h>
-
-namespace Imf {
-namespace RgbaYca {
-
-
-//
-// Width of the chroma subsampling and reconstruction filters
-//
-
-static const int N = 27;
-static const int N2 = N / 2;
-
-
-//
-// Convert a set of primary chromaticities into a set of weighting
-// factors for computing a pixels's luminance, Y, from R, G and B
-//
-
-Imath::V3f computeYw (const Chromaticities &cr);
-
-
-//
-// Convert an array of n RGBA pixels, rgbaIn, to YCA (luminance/chroma/alpha):
-//
-// ycaOut[i].g = Y (rgbaIn[i]);
-// ycaOut[i].r = RY (rgbaIn[i]);
-// ycaOut[i].b = BY (rgbaIn[i]);
-// ycaOut[i].a = aIsValid? rgbaIn[i].a: 1
-//
-// yw is a set of RGB-to-Y weighting factors, as computed by computeYw().
-//
-
-void RGBAtoYCA (const Imath::V3f &yw,
- int n,
- bool aIsValid,
- const Rgba rgbaIn[/*n*/],
- Rgba ycaOut[/*n*/]);
-
-//
-// Perform horizontal low-pass filtering and subsampling of
-// the chroma channels of an array of n pixels. In order
-// to avoid indexing off the ends of the input array during
-// low-pass filtering, ycaIn must have N2 extra pixels at
-// both ends. Before calling decimateChromaHoriz(), the extra
-// pixels should be filled with copies of the first and last
-// "real" input pixel.
-//
-
-void decimateChromaHoriz (int n,
- const Rgba ycaIn[/*n+N-1*/],
- Rgba ycaOut[/*n*/]);
-
-//
-// Perform vertical chroma channel low-pass filtering and subsampling.
-// N scan lines of input pixels are combined into a single scan line
-// of output pixels.
-//
-
-void decimateChromaVert (int n,
- const Rgba * const ycaIn[N],
- Rgba ycaOut[/*n*/]);
-
-//
-// Round the luminance and chroma channels of an array of YCA
-// pixels that has already been filtered and subsampled.
-// The signifcands of the pixels' luminance and chroma values
-// are rounded to roundY and roundC bits respectively.
-//
-
-void roundYCA (int n,
- unsigned int roundY,
- unsigned int roundC,
- const Rgba ycaIn[/*n*/],
- Rgba ycaOut[/*n*/]);
-
-//
-// For a scan line that has valid chroma data only for every other pixel,
-// reconstruct the missing chroma values.
-//
-
-void reconstructChromaHoriz (int n,
- const Rgba ycaIn[/*n+N-1*/],
- Rgba ycaOut[/*n*/]);
-
-//
-// For a scan line that has only luminance and no valid chroma data,
-// reconstruct chroma from the surronding N scan lines.
-//
-
-void reconstructChromaVert (int n,
- const Rgba * const ycaIn[N],
- Rgba ycaOut[/*n*/]);
-
-//
-// Convert an array of n YCA (luminance/chroma/alpha) pixels to RGBA.
-// This function is the inverse of RGBAtoYCA().
-// yw is a set of RGB-to-Y weighting factors, as computed by computeYw().
-//
-
-void YCAtoRGBA (const Imath::V3f &yw,
- int n,
- const Rgba ycaIn[/*n*/],
- Rgba rgbaOut[/*n*/]);
-
-//
-// Eliminate super-saturated pixels:
-//
-// Converting an image from RGBA to YCA, low-pass filtering chroma,
-// and converting the result back to RGBA can produce pixels with
-// super-saturated colors, where one or two of the RGB components
-// become zero or negative. (The low-pass and reconstruction filters
-// introduce some amount of ringing into the chroma components.
-// This can lead to negative RGB values near high-contrast edges.)
-//
-// The fixSaturation() function finds super-saturated pixels and
-// corrects them by desaturating their colors while maintaining
-// their luminance. fixSaturation() takes three adjacent input
-// scan lines, rgbaIn[0], rgbaIn[1], rgbaIn[2], adjusts the
-// saturation of rgbaIn[1], and stores the result in rgbaOut.
-//
-
-void fixSaturation (const Imath::V3f &yw,
- int n,
- const Rgba * const rgbaIn[3],
- Rgba rgbaOut[/*n*/]);
-
-} // namespace RgbaYca
-} // namespace Imf
-
-#endif
projects / opencv / blobdiff