使用 openCV 读取复选框
我正在 Android 应用程序上使用 opencv 库。从相机拍摄的图像中，我想读取一个复选框（我已经知道该复选框的位置），并查看该复选框是否已被填充。即我想知道复选框内的区域是否已部分或完全填充有暗像素。
我使用的是jni接口，所以我使用的是c++语言。我想知道如何找到复选框中这些像素的值，以便我知道大多数复选框都填充了暗（黑色）像素。
I am using the opencv library on an android app. From an image taken from the camera, I want to read a check box (I already have the location of the checkbox), and see if the check box has been filled. i.e. i want to know if the area within the check box has been filled in partially or completely with dark pixels.
I am using the jni interface so i am using the c++ language. I want to know how i can find the values of those pixels in the check box such that i will know that most the check box is filled with dark (black) pixels.
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如果您知道完整的表单是什么样子，那么假设您在某处存储了它的图像。然后，我们可以使用特征点来检测该形式的另一个实例作为相机图像内的平面对象，如 find_obj.cpp 示例。 locatePlanarObject() 函数实际上为我们提供了一个单应性矩阵，我们可以直接将其与 cvWarpPerspective() 一起使用来扭曲捕获的图像以与存储的图像匹配。假设您知道复选框在存储的图像中的位置，我们可以简单直接地比较像素值。在我看来，“暗”像素数量的某种阈值应该有效。
哦，我想你想更多地了解如何访问像素值。这已在许多地方进行了介绍，例如：OpenCV 2.2 中的像素访问
If you know what the complete form looks like, lets assume you have an image of it stored somewhere. We can then use feature points to detect another instance of that form as a planar object inside the camera image, as shown in the find_obj.cpp sample. The locatePlanarObject() function actually gives us a homography matrix, which we can use directly with cvWarpPerspective() to warp back the captured image to match with your stored image. Assuming you know where the check boxes are in the stored image, we can simply and directly compare the pixels values. Some sort of threshold on the amount of "dark" pixels should work IMO.
Oh, I think you want to know more about how to access pixel values. This has been covered in many places, e.g.: Pixel access in OpenCV 2.2