用QT写出图片抖动算法，用于黑白或者黑白红、黑白黄三色墨水屏

以下是用QT实现Floyd-Steinberg算法的示例代码，用于将彩色图像转换为黑白或黑白红、黑白黄三色墨水屏：

#include <QtGui>
#include <QtWidgets>

QImage ditherImage(const QImage& image, int colorMode)
{
    QImage result(image.size(), QImage::Format_Mono);
    int width = image.width();
    int height = image.height();
    int threshold = 128;
    int red, green, blue, gray, newPixel;
    int redThreshold, greenThreshold, blueThreshold;
    int redValue, greenValue, blueValue;

    // 判断颜色模式
    switch (colorMode) {
        case 1:  // 黑白
            threshold = 128;
            break;
        case 2:  // 黑白红
            threshold = 85;
            break;
        case 3:  // 黑白黄
            threshold = 170;
            break;
        default:
            break;
    }

    // 遍历图像像素
    for (int y = 0; y < height; y++) {
        for (int x = 0; x < width; x++) {
            QRgb pixel = image.pixel(x, y);
            red = qRed(pixel);
            green = qGreen(pixel);
            blue = qBlue(pixel);

            // 转换为灰度图像
            gray = (qMax(qMax(red, green), blue) + qMin(qMin(red, green), blue)) / 2;

            // 根据阈值进行二值化处理
            if (gray > threshold) {
                newPixel = 1;
            } else {
                newPixel = 0;
            }

            // 更新像素值
            result.setPixel(x, y, newPixel);

            // 计算误差扩散
            if (newPixel == 0) {
                redValue = red - 0;
                greenValue = green - 0;
                blueValue = blue - 0;
            } else {
                redValue = red - 255;
                greenValue = green - 255;
                blueValue = blue - 255;
            }

            // 分配误差值给周围的像素
            if (x < width - 1) {
                redThreshold = qRed(result.pixel(x + 1, y)) + redValue * 7 / 16;
                greenThreshold = qGreen(result.pixel(x + 1, y)) + greenValue * 7 / 16;
                blueThreshold = qBlue(result.pixel(x + 1, y)) + blueValue * 7 / 16;
                result.setPixel(x + 1, y, qRgb(redThreshold, greenThreshold, blueThreshold));
            }

            if (x > 0 && y < height - 1) {
                redThreshold = qRed(result.pixel(x - 1, y + 1)) + redValue * 3 / 16;
                greenThreshold = qGreen(result.pixel(x - 1, y + 1)) + greenValue * 3 / 16;
                blueThreshold = qBlue(result.pixel(x - 1, y + 1)) + blueValue * 3 / 16;
                result.setPixel(x - 1, y + 1, qRgb(redThreshold, greenThreshold, blueThreshold));
            }

            if (y < height - 1) {
                redThreshold = qRed(result.pixel(x, y + 1)) + redValue * 5 / 16;
                greenThreshold = qGreen(result.pixel(x, y + 1)) + greenValue * 5 / 16;
                blueThreshold = qBlue(result.pixel(x, y + 1)) + blueValue * 5 / 16;
                result.setPixel(x, y + 1, qRgb(redThreshold, greenThreshold, blueThreshold));
            }

            if (x < width - 1 && y < height - 1) {
                redThreshold = qRed(result.pixel(x + 1, y + 1)) + redValue * 1 / 16;
                greenThreshold = qGreen(result.pixel(x + 1, y + 1)) + greenValue * 1 / 16;
                blueThreshold = qBlue(result.pixel(x + 1, y + 1)) + blueValue * 1 / 16;
                result.setPixel(x + 1, y + 1, qRgb(redThreshold, greenThreshold, blueThreshold));
            }
        }
    }

    return result;
}

在使用时，可以通过调用`ditherImage()`函数将彩色图像转换为黑白或黑白红、黑白黄三色墨水屏。其中，`image`参数是输入图像，`colorMode`参数指定颜色模式（1代表黑白，2代表黑白红，3代表黑白黄），返回值是输出图像。