1bit、2bit、4bit图像解压缩为8bit

最新推荐文章于 2025-12-31 21:25:26 发布

原创最新推荐文章于 2025-12-31 21:25:26 发布 · 181 阅读

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1bit → 8bit 解压（黑白图像）

std::shared_ptr<unsigned char> Convert1bitTo8bit(const std::shared_ptr<unsigned char>& input, int width, int height)
{
    size_t pixelCount = width * height;
    std::shared_ptr<unsigned char> output(new unsigned char[pixelCount], std::default_delete<unsigned char[]>());

    for (size_t i = 0; i < pixelCount; ++i) {
        size_t byteIndex = i / 8;
        size_t bitOffset = 7 - (i % 8);
        unsigned char bit = (input.get()[byteIndex] >> bitOffset) & 0x01;
        output.get()[i] = bit ? 255 : 0;
    }

    return output;
}

2bit → 8bit 解压（4级灰度）

std::shared_ptr<unsigned char> Convert2bitTo8bit(const std::shared_ptr<unsigned char>& input, int width, int height)
{
    size_t pixelCount = width * height;
    std::shared_ptr<unsigned char> output(new unsigned char[pixelCount], std::default_delete<unsigned char[]>());

    for (size_t i = 0; i < pixelCount; ++i) {
        size_t byteIndex = i / 4;
        size_t bitOffset = (3 - (i % 4)) * 2;
        unsigned char bits = (input.get()[byteIndex] >> bitOffset) & 0x03;
        output.get()[i] = bits * 85; // 0→0, 1→85, 2→170, 3→255
    }

    return output;
}

4bit → 8bit 解压（16级灰度）

std::shared_ptr<unsigned char> Convert4bitTo8bit(const std::shared_ptr<unsigned char>& input, int width, int height)
{
    size_t pixelCount = width * height;
    std::shared_ptr<unsigned char> output(new unsigned char[pixelCount], std::default_delete<unsigned char[]>());

    for (size_t i = 0; i < pixelCount; ++i) {
        size_t byteIndex = i / 2;
        bool high = (i % 2 == 0);
        unsigned char bits = high ? (input.get()[byteIndex] >> 4) : (input.get()[byteIndex] & 0x0F);
        output.get()[i] = bits * 17; // 0→0, 1→17, ..., 15→255
    }

    return output;
}