目錄

一，存儲圖像

1，存儲 imwrite

2，編碼格式

3，圖片位深

二，讀取圖像

1，讀取 imread

2，讀取類型 ImreadModes

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一，存儲圖像

1，存儲 imwrite

imwrite("D:/im2.jpg", image2);

第三個參數缺省了。

2，編碼格式

jpg是有損壓縮，png是無損壓縮，如果對圖片要求很高的，還是用png好一點。

3，圖片位深

32F類型的圖片，像這樣存下來之后會變成8U的，讀取之后也是8U的，

即使再轉換成32F的，也可能和原圖有差異。

二，讀取圖像

1，讀取 imread

string path = "D:/im2.jpg"; Mat image = imread(path, IMREAD_UNCHANGED); if (!image.data) {cout << "imread fail\n";return; }

第二個參數是ImreadModes類型的枚舉，表示讀取的通道數

返回的是一個Mat類型的對象。

成員data是uchar的指針，如果讀取失敗那么指針為空

2，讀取類型 ImreadModes

ImreadModes的源代碼：

enum ImreadModes {IMREAD_UNCHANGED = -1, //!< If set, return the loaded image as is (with alpha channel, otherwise it gets cropped). Ignore EXIF orientation.IMREAD_GRAYSCALE = 0, //!< If set, always convert image to the single channel grayscale image (codec internal conversion).IMREAD_COLOR = 1, //!< If set, always convert image to the 3 channel BGR color image.IMREAD_ANYDEPTH = 2, //!< If set, return 16-bit/32-bit image when the input has the corresponding depth, otherwise convert it to 8-bit.IMREAD_ANYCOLOR = 4, //!< If set, the image is read in any possible color format.IMREAD_LOAD_GDAL = 8, //!< If set, use the gdal driver for loading the image.IMREAD_REDUCED_GRAYSCALE_2 = 16, //!< If set, always convert image to the single channel grayscale image and the image size reduced 1/2.IMREAD_REDUCED_COLOR_2 = 17, //!< If set, always convert image to the 3 channel BGR color image and the image size reduced 1/2.IMREAD_REDUCED_GRAYSCALE_4 = 32, //!< If set, always convert image to the single channel grayscale image and the image size reduced 1/4.IMREAD_REDUCED_COLOR_4 = 33, //!< If set, always convert image to the 3 channel BGR color image and the image size reduced 1/4.IMREAD_REDUCED_GRAYSCALE_8 = 64, //!< If set, always convert image to the single channel grayscale image and the image size reduced 1/8.IMREAD_REDUCED_COLOR_8 = 65, //!< If set, always convert image to the 3 channel BGR color image and the image size reduced 1/8.IMREAD_IGNORE_ORIENTATION = 128 //!< If set, do not rotate the image according to EXIF's orientation flag.};

-1 IMREAD_UNCHANGED 表示按照圖片本身的通道數

0 IMREAD_GRAYSCALE 表示灰度圖像，即單通道

1?IMREAD_COLOR 表示按照3通道

總結

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