When extracting the RGB values from an NSImage with a transparent background I obtain the correct RGB values for the actual colored object within a particular image, but I am also getting RGB values of (0,0,0) even though there are no black pixels in sight within the particular image I test with. My guess was that I am getting (0,0,0) from the parts of the transparent image. How do I only get the RGB values from the image minus the transparent background. This behavior happens when I resize the image and extract the pixels values with the code down below.
Resizing Code (credit):
open func resizeImage(image:NSImage, newSize:NSSize) -> NSImage{
let rep = NSBitmapImageRep(bitmapDataPlanes: nil, pixelsWide: Int(newSize.width), pixelsHigh: Int(newSize.height), bitsPerSample: 8, samplesPerPixel: 4, hasAlpha: true, isPlanar: false, colorSpaceName: NSDeviceRGBColorSpace, bytesPerRow: 0, bitsPerPixel: 0)
rep?.size = newSize
NSGraphicsContext.saveGraphicsState()
let bitmap = NSGraphicsContext.init(bitmapImageRep: rep!)
NSGraphicsContext.setCurrent(bitmap)
image.draw(in: NSMakeRect(0, 0, newSize.width, newSize.height), from: NSMakeRect(0, 0, image.size.width, image.size.height), operation: .sourceOver, fraction: CGFloat(1))
let newImage = NSImage(size: newSize)
newImage.addRepresentation(rep!)
return newImage
}
The code I used to extract the RGB values from an NSImage is down below:
RGB Extraction Code (credit) :
extension NSImage {
func pixelData() -> [Pixel] {
var bmp = self.representations[0] as! NSBitmapImageRep
var data: UnsafeMutablePointer<UInt8> = bmp.bitmapData!
var r, g, b, a: UInt8
var pixels: [Pixel] = []
NSLog("%d", bmp.pixelsHigh)
NSLog("%d", bmp.pixelsWide)
for var row in 0..<bmp.pixelsHigh {
for var col in 0..<bmp.pixelsWide {
r = data.pointee
data = data.advanced(by: 1)
g = data.pointee
data = data.advanced(by: 1)
b = data.pointee
data = data.advanced(by: 1)
a = data.pointee
data = data.advanced(by: 1)
pixels.append(Pixel(r: r, g: g, b: b, a: a))
}
}
return pixels
}
}
class Pixel {
var r: Float!
var g: Float!
var b: Float!
init(r: UInt8, g: UInt8, b: UInt8, a: UInt8) {
self.r = Float(r)
self.g = Float(g)
self.b = Float(b)
}
}
I have also tried changing the operation parameter in the draw method of the resizing code to .copy, but with no luck.
