how to test the colour of a pixel?

[togFox]

I'm dabbling into artificial intelligence more And more and many techniques is to 'scan ' an image and store pixel information into a 2D table then feed that table into a neural network.

If I draw/ display a graphic on the screen with Love 2D, how might I get RGB values for the pixel at coordinates (50, 50)?

Assume a random image was loaded and displayed with love.graphucs draw()

[pgimeno]

Ironic that you're asking this when in a neighbouring thread someone is asking about love.graphics.captureScreenshot

ImageData is the type you need if you want to read pixels.

[dusoft]

I'm dabbling into artificial intelligence more And more and many techniques is to 'scan ' an image and store pixel information into a 2D table then feed that table into a neural network.

If I draw/ display a graphic on the screen with Love 2D, how might I get RGB values for the pixel at coordinates (50, 50)?

Assume a random image was loaded and displayed with love.graphucs draw()

Code: Select all

mask = love.image.newImageData('assets/images/example.png')
local r, g, b, a = mask:getPixel(x, y)

[BrotSagtMist]

love.graphics.captureScreenshot( callback ) will turn your screen into image data passed to callback.
Your callback should then use https://love2d.org/wiki/ImageData:mapPixel to get the pixel values.
Callback can be a thread stack meaning that you can deciper the data on another thread while the game is running, thats so far the smartest solution.

[togFox]

Oh - that simple? I was expecting a far more complicated response!

[zorg]

Oh - that simple? I was expecting a far more complicated response!

Well, if you do want to draw it out first, and then read the image back with captureScreenshot, for whatever convoluted reason, that will have a gigantic delay due to the data going this way: RAM -> VRAM -> RAM.

If you can just use ImageData and manipulate that, you save yourself that hassle.

[togFox]

Yeah - performance is something I'll need to check and ensure I don't scan too many pixels too quickly

[RNavega]

An alternative to capturing a screenshot is using a render target, AKA the Canvas object.
Check the samples for how to use it, including its newImageData() function, comparable to captureScreenshot().