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Aimjiel

PixelSearch: Find redish/greenish/yellowish colors

6 posts in this topic

Hi All,

I am looking for a way to tell if a pixel is a an unspecific tint/shade of a color. For instance, I want to know if it's red-ish, instead of feeding in just a straightforward color.

I don't fully understand how Autoit sees color, or how color works altogether, if someone could point me in the right direction, that'd be awesome!

Cheers,

Jason

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Function PixelSearch

Look at the shade-variation parameter.

Let this be a lesson not to code until 4 a.m.

Thank you very much!

/Jason

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You bet. :)


- Bruce /*somdcomputerguy */  If you change the way you look at things, the things you look at change.

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I'm not sure if PixelSearch is the answer to your problem. You need to read up on how RGB works. I'm no expert but had to look into it for a small project recently.

Basically "red-ish" as you describe is the hue. Hue is the relative difference of that channel (R ) over the other channels (G & B). So even if you find the red values that you are looking for (with PixelSearch) there is no guarantee it will appear red without knowing what the other two channels are - it could appear grey (all channels equal) or even green or blue (if those channels are greater relative to red). See Wiki.

PixelGetColor or _GDIPlus_BitmapLockBits are your friends. Then you might want to look into _ColorConvertRGBtoHSL to calculate hue. I believe this will give hue as an angle (in revolutions? (360° = 1 rev) the help file is unusally not so helpful here). For red you'd accept values of 0° ± say 15°.

QED

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i suggest PixelGetColor, from there you can BitAnd to get the red, green and blue values and run your own testing:

this isn't anything great, but it will return the most visible colour (default scite4autoit3 from last year's background colour returns #0000F9 from this) or the actual colour found if it doesn't think there's something noticeable

Func getHue($x, $y)
    Local $color = PixelGetColor($x, $y)
    Local $red = BitShift(BitAnd($color, 0xff0000), 16), $green = BitShift(BitAnd($color, 0xff00), 8), $blue = BitAnd($color, 255)
    Local $red2 = $red, $green2 = $green, $blue2 = $blue
    If $red > 30 Then 
        $red2 = $red - 5
    EndIf
    If $green > 30 Then 
        $green2 = $green - 5
    EndIf
    If $blue > 30 Then
        $blue2 = $blue - 5
    EndIf
    If ($red > $green) And ($red > $blue) Then
        If ($red2 >= $green) And ($red2 >= $blue) Then
            Return BitShift($red, -16)
        EndIf
    EndIf
    If ($green > $red) And ($green > $blue) Then
        If ($green2 >= $red) And ($green2 >= $blue) Then
            Return BitShift($green, -8)
        EndIf
    EndIf
    If ($blue > $green) And ($red < $blue) Then
        If ($blue2 >= $green) And ($red <= $blue2) Then
            Return $blue
        EndIf
    EndIf
    Return $color
EndFunc

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