使用freeimage将数据保存为png图片格式

Linux（Ubuntu16.04）环境下配置freeimage库

1.下载https://freeimage.sourceforge.io/
2.安装https://blog.csdn.net/woainishifu/article/details/71451119(可以参考，我下载的版本比他的高，直接安装没有出错)
3.使用，编译时加上-lfreeimage链接到库

调用freeimage库保存图片

static void save_png()
{
	const char* fileName = "test.png";
	int w = 250;
	int h = 250;
	BYTE* pixels = new BYTE[w * h * 4];
	for (int y = 0; y < h; y++)
	{
		for (int x = 0; x < w; x++)
		{
			int i = x * w + y;
			pixels[i * 4 + 0] = ColorMap[y][2];
			pixels[i * 4 + 1] = ColorMap[y][1];
			pixels[i * 4 + 2] = ColorMap[y][0];
			pixels[i * 4 + 3] = 255;
		}
	}
	//save-----------------------------------------------------------------
	//图片格式	
	FREE_IMAGE_FORMAT fif = FIF_PNG;
	//图片像素深度	
	int bpp = 8 * 4;
	//图片宽
	int width = w;
	//图片高
	int height = h;
	//图片每行像素(freeimage自动做了32位对齐)
	int pitch = width * 4;
	//图片像素数组
	BYTE* bits = pixels;
	//图片所有数据
	FIBITMAP* dib = FreeImage_ConvertFromRawBits(bits, width, height, pitch, bpp, 0, 0, 0);
	FreeImage_Save(FIF_PNG, dib, fileName);
	//释放
	FreeImage_Unload(dib);
	delete[] pixels;
}