*UPDATED* find coordinates on a picture...

[cyborg]

hi!
i want to make a program where the user can load a picture
and click the backgroundcolor, then the program calculated the cordinates around the picture....
hmm...
it a bit more complicated than that...

just look at this picture and you'll understand!





the coordinates can be printed in a textbox or in a txt file or anything!

please help me with this!

[cyborg]

please help me!

[Alien_poo]

LOL! nice animation....

the only way I would see to do this si to scan every little pixel one by one and store it's color in an array...

[cyborg]

yeah...but then?

and i dont know how to do arrays...

[cyborg]

i've made a program that can open files like this drawn by hand...

[Arc]

What you want is impossible. How would a program even know whre to start tracing? How would it know what parts to trace? Maybe with a simple picture like you had(A Black Smiley Face on a red background) it would be possible but still very difficult, and there would be no way to write an algorithm that would work for any picture.



It's just not possible.

[cyborg]

oh....forgit to mention:
the program is not ment to draw lines!
just store coordinates in a textbox or textfile...

[cyborg]

it IS possible!
i've used another program that does the same thing...

i dont know how it works, but it works!

[cyborg]

have you used the floodfill api?
how can that function know where to paint?

[cyborg]

i know i can make a program that draws lines around those objects, but i can do one that does it in the right order...

[cyborg]

when the user clicks on the background color the program knows where to look...
between that color and a color thats not equal to the BG color...

[Arc]

Not even photoshop can do what you are asking I seriously doubt you'll find an answer on this VB forum

[SLH]

If i understand you correctly, you want to detect everywhere where there is a change in colour, from the background to something else?? Am i correct?

If so, your logic would go something like this.

Option Explicit
Dim i As Integer, j As Integer
Dim BackGroundColour As Long
Private Type typPixel
    x As Integer
    y As Integer
End Type
Dim Edge() As typPixel
Private Sub FindEdges
    Pic.ScaleMode = 3 'Pixel
    For i = 2 To Pic.ScaleHeight
        For j = 1 To Pic.ScaleWidth
            If Pic.Point(j, i) = BackGroundColour And Pic.Point(j, i - 1) <> BackGroundColour Then
                ReDim Preserve Edge(UBound(Edge) + 1)
                Edge(UBound(Edge)).x = j
                Edge(UBound(Edge)).y = i
            End If
        Next j
    Next i
    
    For i = 1 To Pic.ScaleHeight - 1
        For j = 1 To Pic.ScaleWidth
            If Pic.Point(j, i) = BackGroundColour And Pic.Point(j, i + 1) <> BackGroundColour Then
                ReDim Preserve Edge(UBound(Edge) + 1)
                Edge(UBound(Edge)).x = j
                Edge(UBound(Edge)).y = i
            End If
        Next j
    Next i
    
    For i = 1 To Pic.ScaleHeight
        For j = 2 To Pic.ScaleWidth
            If Pic.Point(j, i) = BackGroundColour And Pic.Point(j - 1, i) <> BackGroundColour Then
                ReDim Preserve Edge(UBound(Edge) + 1)
                Edge(UBound(Edge)).x = j
                Edge(UBound(Edge)).y = i
            End If
        Next j
    Next i
    
    For i = 1 To Pic.ScaleHeight
        For j = 1 To Pic.ScaleWidth - 1
            If Pic.Point(j, i) = BackGroundColour And Pic.Point(j + 1, i) <> BackGroundColour Then
                ReDim Preserve Edge(UBound(Edge) + 1)
                Edge(UBound(Edge)).x = j
                Edge(UBound(Edge)).y = i
            End If
        Next j
    Next i
End Sub

This will check every pixel, and against the ones next to it, for a change in colour. You may need to do diaganols, but that won't be too difficult.

[plenderj]

Yes I would suggest an approach as used by SLH.
That is the only sensible way to approach the problem.

[cyborg]

yeah! SLH....you know what i want....but i also (if its possible) want the program to sort the coordinates as the .gif animation shows...

i get the
"Subscript out of range"
error on
"ReDim Preserve Edge(UBound(Edge) + 1)"

what wrong?

[SLH]

Sorry, try this code:

Option Explicit
Dim i As Integer, j As Integer
Dim BackGroundColour As Long
Private Type typPixel
    x As Integer
    y As Integer
End Type
Dim Edge() As typPixel
Private Sub FindEdges
    [B]ReDim Edge(0)[/B]
    Pic.ScaleMode = 3 'Pixel
    For i = 2 To Pic.ScaleHeight
        For j = 1 To Pic.ScaleWidth
            If Pic.Point(j, i) = BackGroundColour And Pic.Point(j, i - 1) <> BackGroundColour Then
                ReDim Preserve Edge(UBound(Edge) + 1)
                Edge(UBound(Edge)).x = j
                Edge(UBound(Edge)).y = i
            End If
        Next j
    Next i
    
    For i = 1 To Pic.ScaleHeight - 1
        For j = 1 To Pic.ScaleWidth
            If Pic.Point(j, i) = BackGroundColour And Pic.Point(j, i + 1) <> BackGroundColour Then
                ReDim Preserve Edge(UBound(Edge) + 1)
                Edge(UBound(Edge)).x = j
                Edge(UBound(Edge)).y = i
            End If
        Next j
    Next i
    
    For i = 1 To Pic.ScaleHeight
        For j = 2 To Pic.ScaleWidth
            If Pic.Point(j, i) = BackGroundColour And Pic.Point(j - 1, i) <> BackGroundColour Then
                ReDim Preserve Edge(UBound(Edge) + 1)
                Edge(UBound(Edge)).x = j
                Edge(UBound(Edge)).y = i
            End If
        Next j
    Next i
    
    For i = 1 To Pic.ScaleHeight
        For j = 1 To Pic.ScaleWidth - 1
            If Pic.Point(j, i) = BackGroundColour And Pic.Point(j + 1, i) <> BackGroundColour Then
                ReDim Preserve Edge(UBound(Edge) + 1)
                Edge(UBound(Edge)).x = j
                Edge(UBound(Edge)).y = i
            End If
        Next j
    Next i
End Sub

NB: This code will take a couple of seconds on a large image (well, even a small one).

As for drawing lines, it would be easy to highlight the edges, but to make it join them up, would require A LOT of thinking....

[cyborg]

yeah!
nice!
this code gets me the coordinates

but do you know any way to sort them?

[SLH]

What do you mean by 'sorted', do you want the program to calculate the best way to join then up (like in your pic)?? If so that would be very difficult.


P.S. Just out of interest, are you making a program that shows where a 'jig-saw' would need to cut (because that's what it looks like).

[cyborg]

yes, i mean that the program should find the best way to draw the lines...

and no! im making a transparent region generator for winamp skins!

[SLH]

How are you going to use the lines created to generate a transparency region, surely it'll end up being the same region as the bacoground??

[cyborg]

winamp loads the transparecy regions in a strange way...
you have to do a file that looks like this fore example:


if there is a line with 6 different coordinates
(170,36)
(200,36)
(226,36)
etc...

it has to look like this:


[Normal]
NumPoints = 6
PointList = 170,36,200,36,226,36,239,36,255,36,34,63


this is the line where winamp is going to "cut" off the background

[SLH]

Ok, as i've said a couple of times in this post, i'll have a think