为像素指定负值 [英] Assigining a negative value to a pixel

问题描述

使用某些标准，图像中有一些我不感兴趣的像素。所以，我想忽略它们。我只是想问一下我所遵循的方法是否可以接受。我已经为这些像素分配了一个负值。这可以接受吗？而且，当像素具有负值时，它意味着什么？它会在图像上有一些表示吗？

Using some criterion, there are some pixels in the image which I'm not interested in. So, I would like to neglect them. I just want to ask if the approach I have followed is acceptable. I have assigned such pixels a negative value. Would that be acceptable? And, what does it mean when a pixel has a negative value? Will it have some representation on the image?

推荐答案

如果您的数据类型允许它，如有符号整数（CV_32S）或浮点数（CV_32F或CV_64F），使用负值非常有意义，这是一种指定忽略像素的常用方法。在这种情况下，除了对它的解释之外，对负值没有特殊含义。

If your data type allows it, like signed integer (CV_32S) or floating point (CV_32F or CV_64F), it makes perfect sense to use negative values and it is a very common way to specify ignored pixels. In this case there is no special meaning to a negative value except your interpretation of it.

另一方面，如果你使用8位无符号图像（CV_8U），这可能会导致错误：它可能被截断为零或转换为[0,255] ]使用modulo-256添加，具体取决于您的opencv版本。在最坏的情况下，如果以非常糟糕的方式访问像素数据，它也可能溢出到邻居像素并修改它们的值。因此，如果使用8位图像，则应该使用掩码来指定忽略的像素，如phyrox所述。

On the other hand, if you use 8-bit unsigned images (CV_8U), this may lead to errors : it may either be truncated to zero or converted to [0,255] using modulo-256 addition, depending on your version of opencv. In the worst case, it may also overflow to neighbor pixels and modify their values, if you access pixel data in a very bad way. So if you work with 8-bit images, you should rather use a mask to specify ignored pixels, as phyrox explained.

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