视觉处理常用的一些概念和微小算法

Posted 2020-10-08

~ false positives 虚警率

~ false negative 漏检率

~ recall 检出率/查全率

~ precision 正确率

~ intergral images 积分帧(算法),该算法能够快速算出区块的灰度和

An integral image helps you rapidly calculate summations over image subregions. Every pixel in an integral image is the summation of the pixels above and to the left of it.

To calculate the summation of a subregion of an image, you can use the corresponding region of its integral image. For example, in the input image below, the summation of the shaded region becomes a simple calculation using four reference values of the rectangular region in the corresponding integral image. The calculation becomes, 46 – 22 – 20 + 10 = 14. The calculation subtracts the regions above and to the left of the shaded region. The area of overlap is added back to compensate for the double subtraction.

In this way, you can calculate summations in rectangular regions rapidly, irrespective of the filter size.