hyperion.ng/libsrc/utils/ImageResampler.cpp

#include "utils/ImageResampler.h"

ImageResampler::ImageResampler() :
	_horizontalDecimation(1),
	_verticalDecimation(1),
	_cropLeft(0),
	_cropRight(0),
	_cropTop(0),
	_cropBottom(0),
	_videoMode(VIDEO_2D)
{

}

ImageResampler::~ImageResampler()
{

}

void ImageResampler::setHorizontalPixelDecimation(int decimator)
{
	_horizontalDecimation = decimator;
}

void ImageResampler::setVerticalPixelDecimation(int decimator)
{
    _verticalDecimation = decimator;
}

void ImageResampler::setCropping(int cropLeft, int cropRight, int cropTop, int cropBottom)
{
    _cropLeft = cropLeft;
    _cropRight = cropRight;
    _cropTop = cropTop;
    _cropBottom = cropBottom;
}

void ImageResampler::set3D(VideoMode mode)
{
	_videoMode = mode;
}

void ImageResampler::processImage(const uint8_t * data, int width, int height, int lineLength, PixelFormat pixelFormat, Image<ColorRgb> &outputImage) const
{
	int cropLeft = _cropLeft;
	int cropRight = _cropRight;
	int cropTop = _cropTop;
	int cropBottom = _cropBottom;

	// handle 3D mode
	switch (_videoMode)
	{
	case VIDEO_3DSBS:
		cropRight = width/2;
		break;
	case VIDEO_3DTAB:
		cropBottom = height/2;
		break;
	default:
		break;
	}

	// calculate the output size
    int outputWidth = (width - cropLeft - cropRight - _horizontalDecimation/2 + _horizontalDecimation - 1) / _horizontalDecimation;
    int outputHeight = (height - cropTop - cropBottom - _verticalDecimation/2 + _verticalDecimation - 1) / _verticalDecimation;
	outputImage.resize(outputWidth, outputHeight);

	for (int yDest = 0, ySource = cropTop + _verticalDecimation/2; yDest < outputHeight; ySource += _verticalDecimation, ++yDest)
	{
        for (int xDest = 0, xSource = cropLeft + _horizontalDecimation/2; xDest < outputWidth; xSource += _horizontalDecimation, ++xDest)
		{
			ColorRgb & rgb = outputImage(xDest, yDest);

			switch (pixelFormat)
			{
			case PIXELFORMAT_UYVY:
				{
                    int index = lineLength * ySource + xSource * 2;
					uint8_t y = data[index+1];
					uint8_t u = ((xSource&1) == 0) ? data[index  ] : data[index-2];
					uint8_t v = ((xSource&1) == 0) ? data[index+2] : data[index  ];
					yuv2rgb(y, u, v, rgb.red, rgb.green, rgb.blue);
				}
				break;
			case PIXELFORMAT_YUYV:
				{
                    int index = lineLength * ySource + xSource * 2;
					uint8_t y = data[index];
					uint8_t u = ((xSource&1) == 0) ? data[index+1] : data[index-1];
					uint8_t v = ((xSource&1) == 0) ? data[index+3] : data[index+1];
					yuv2rgb(y, u, v, rgb.red, rgb.green, rgb.blue);
				}
				break;
            case PIXELFORMAT_BGR16:
                {
                    int index = lineLength * ySource + xSource * 2;
                    rgb.blue  = (data[index] & 0x1f) << 3;
                    rgb.green = (((data[index+1] & 0x7) << 3) | (data[index] & 0xE0) >> 5) << 2;
                    rgb.red   = (data[index+1] & 0xF8);
                }
                break;
            case PIXELFORMAT_BGR24:
                {
                    int index = lineLength * ySource + xSource * 3;
                    rgb.blue  = data[index  ];
                    rgb.green = data[index+1];
                    rgb.red   = data[index+2];
                }
                break;
            case PIXELFORMAT_RGB32:
                {
                    int index = lineLength * ySource + xSource * 4;
                    rgb.red   = data[index  ];
                    rgb.green = data[index+1];
                    rgb.blue  = data[index+2];
                }
                break;
            case PIXELFORMAT_BGR32:
                {
                    int index = lineLength * ySource + xSource * 4;
                    rgb.blue  = data[index  ];
                    rgb.green = data[index+1];
                    rgb.red   = data[index+2];
                }
                break;
            case PIXELFORMAT_NO_CHANGE:
                std::cerr << "Invalid pixel format given" << std::endl;
				break;
			}
		}
	}
}

uint8_t ImageResampler::clamp(int x)
{
	return (x<0) ? 0 : ((x>255) ? 255 : uint8_t(x));
}

void ImageResampler::yuv2rgb(uint8_t y, uint8_t u, uint8_t v, uint8_t &r, uint8_t &g, uint8_t &b)
{
	// see: http://en.wikipedia.org/wiki/YUV#Y.27UV444_to_RGB888_conversion
	int c = y - 16;
	int d = u - 128;
	int e = v - 128;

	r = clamp((298 * c + 409 * e + 128) >> 8);
	g = clamp((298 * c - 100 * d - 208 * e + 128) >> 8);
	b = clamp((298 * c + 516 * d + 128) >> 8);
}