我正在尝试转换 BufferedImage
至 Mat
对于从 Internet 下载的具有不同文件类型的大量图像。因为我是从网站上抓取图片,所以我无法控制文件格式。我可以轻松地将它们加载到 BufferedImage
不知道格式,但将它们转换为 Mat
,我需要知道图像类型。不幸的是,CvType
之间似乎没有很好的对应关系。和 BufferedImage
类型。
CvType
表示格式为 CV_<bit-depth>{U|S|F}C<number_of_channels>
的图像类型其中 U
是无符号字符,S
是有符号的字符,F
是 float 的。
BufferedImage
类型在表示上有更多变化,包括对称 channel ( TYPE_4BYTE_ABGR
)、不同数量的位 ( TYPE_BYTE_BINARY
),以及任何索引字节图像 ( TYPE_BYTE_INDEXED
)。
根据文档,我尝试完成自己的通信。
BufferedImage imgBuffer = ImageIO.read(new File("example.gif"));
//Save file as reference
File outputfile = new File("temp/image.png");
ImageIO.write(imgBuffer, "png", outputfile);
//My correspondance
int curCVtype = -1;
switch (imgBuffer.getType()) {
case BufferedImage.TYPE_3BYTE_BGR:
curCVtype = CvType.CV_8UC3;
break;
case BufferedImage.TYPE_BYTE_GRAY:
curCVtype = CvType.CV_8UC1;
break;
case BufferedImage.TYPE_INT_BGR:
case BufferedImage.TYPE_INT_RGB:
curCVtype = CvType.CV_8SC3;
break;
case BufferedImage.TYPE_INT_ARGB:
case BufferedImage.TYPE_INT_ARGB_PRE:
curCVtype = CvType.CV_8SC4;
break;
default:
// The types not handled by my correspondence
// BufferedImage.TYPE_BYTE_BINARY;
// BufferedImage.TYPE_USHORT_GRAY;
// BufferedImage.TYPE_4BYTE_ABGR;
// BufferedImage.TYPE_4BYTE_ABGR_PRE;
// BufferedImage.TYPE_BYTE_INDEXED;
// BufferedImage.TYPE_CUSTOM;
System.out.println("Unsupported format:" + imgBuffer.getType());
//Here I choose a default type
curCVtype = CvType.CV_8SC3;
}
//Convert to Mat
byte[] pixels = ((DataBufferByte) imgBuffer.getRaster().getDataBuffer()).getData();
Mat img = new Mat(imgBuffer.getHeight(), imgBuffer.getWidth(), curCVtype);
img.put(0, 0, pixels);
//Write the output to compare
Imgcodecs.imwrite("temp/image_mat.png", img);
问题
- 我做的正确吗?或者有更好的方法吗?
- 在我的默认情况下,类型的正确对应是什么?
例子
转换为Mat后输出PNG。 BufferedImage
类型是 TYPE_BYTE_INDEXED
转换为 CvType.CV_8SC3
转换为Mat后输出PNG。 BufferedImage
类型是 TYPE_BYTE_INDEXED
转换为 CvType.CV_8UC3
资源:
我的起始代码来自Converting BufferedImage to Mat in opencv .
我对 CvTypes 的了解来自 What's the difference between cvtype values in OPENCV? .
最佳答案
感谢 Miki 和 haraldK 提供的有用评论。
我针对未知图像类型的解决方案以 RGB 格式检索像素,并将它们放入 CvType.CV_8UC4
的 Mat
中。最后,使用 Core.mixChannels
对 channel 重新排序到 OpenCV 首选顺序:BGR(A)。
此示例仅对未知图像类型的 channel 进行重新排序,但所有非 BGR 图像类型都需要重新排序。
BufferedImage imgBuffer = ImageIO.read(new File("example.gif"));
//Save image as reference
File outputfile = new File("temp/image.png");
ImageIO.write(imgBuffer, "png", outputfile);
//My correspondance
int curCVtype = CvType.CV_8UC4; //Default type
boolean supportedType = true;
switch (imgBuffer.getType()) {
case BufferedImage.TYPE_3BYTE_BGR:
curCVtype = CvType.CV_8UC3;
break;
case BufferedImage.TYPE_BYTE_GRAY:
case BufferedImage.TYPE_BYTE_BINARY:
curCVtype = CvType.CV_8UC1;
break;
case BufferedImage.TYPE_INT_BGR:
case BufferedImage.TYPE_INT_RGB:
curCVtype = CvType.CV_32SC3;
break;
case BufferedImage.TYPE_INT_ARGB:
case BufferedImage.TYPE_INT_ARGB_PRE:
curCVtype = CvType.CV_32SC4;
break;
case BufferedImage.TYPE_USHORT_GRAY:
curCVtype = CvType.CV_16UC1;
break;
case BufferedImage.TYPE_4BYTE_ABGR:
case BufferedImage.TYPE_4BYTE_ABGR_PRE:
curCVtype = CvType.CV_8UC4;
break;
default:
// BufferedImage.TYPE_BYTE_INDEXED;
// BufferedImage.TYPE_CUSTOM;
System.out.println("Unsupported format:" + imgBuffer.getType());
supportedType = false;
}
//Convert to Mat
Mat img = new Mat(imgBuffer.getHeight(), imgBuffer.getWidth(), curCVtype);
if (supportedType) {
// Insert pixel buffer directly
byte[] pixels = ((DataBufferByte) imgBuffer.getRaster().getDataBuffer()).getData();
img.put(0, 0, pixels);
} else {
// Convert to RGB first
int height = imgBuffer.getHeight();
int width = imgBuffer.getWidth();
int[] pixels = imgBuffer.getRGB(0, 0, width - 1, height - 1, null, 0, width);
// Convert ints to bytes
ByteBuffer byteBuffer = ByteBuffer.allocate(pixels.length * 4);
IntBuffer intBuffer = byteBuffer.asIntBuffer();
intBuffer.put(pixels);
byte[] pixelBytes = byteBuffer.array();
img.put(0, 0, pixelBytes);
// Reorder the channels for Opencv BGRA format from
// BufferedImage ARGB format
Mat imgMix = img.clone();
ArrayList<Mat> imgSrc = new ArrayList<Mat>();
imgSrc.add(imgMix);
ArrayList<Mat> imgDest = new ArrayList<Mat>();
imgDest.add(img);
int[] fromTo = { 0, 3, 1, 2, 2, 1, 3, 0 }; //Each pair is a channel swap
Core.mixChannels(imgSrc, imgDest, new MatOfInt(fromTo));
}
//Save output image
Imgcodecs.imwrite("temp/image_mat.png", img);
关于java - 如何匹配BufferedImage和Mat的颜色模型?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/33403526/