Image fundamentals
Before we can start with image analysis, we first need to briefly consider what is an image... and the different types of image that QuPath can handle.
Digital images are composed of pixels. The word pixel is derived from picture element, and, as far as the computer is concerned, each pixel is just a number.
When the image data is displayed, the values of pixels are usually converted into squares of particular colors or shades of gray – but this is only for our benefit to allow us to get a fast impression of the image contents, i.e. the approximate values of pixels and where they are in relation to one another. When it comes to processing and analysis, we need to delve into the real data: the numbers.
Typically, images are shown on screen with colors and shades of gray. However...
...underlying the display is a large array of numbers - which are the pixel values.
The pixel values (numbers) are the raw data of the image. The goal of image analysis is to make sense of these values, and find meaningful patterns within them.
Interpreting pixel values isn't straightforward.
(see here for more information about this)
Additive vs. subtractive
Quantitative vs.... not so Quantitative
Separating stains