distance between two pixels using VB.

Posted on 2001-07-18
Last Modified: 2010-08-05
   I have a BW scanned image that is saved as a bmp, basically I want to figure out it's length by measuring the top-most black pixel and the bottom pixel.  How do I find these pixels?  I also would like to find the width at a certain number of inches, pixels, or whatever down the image.  How do I do this also?  I figure it would be easy if I started at the top left pixel and scaned row by row till I found a black one but I have no idea how to do this.  Can someone help me?

Thanks in Advance,
Question by:Cide
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LVL 22

Accepted Solution

rspahitz earned 150 total points
ID: 6296056
Point Method

Returns, as a long integer, the red-green-blue (RGB) color of the specifiedpoint on a Form or PictureBox. Doesn't supportnamed arguments.


object.Point(x, y)

Use a loop something like this:

for y=0 to Picture1.height
  for x=0 to Picture1.width
    if Picture1.Point(x,y) = vbBlack then
      msgbox "Found it at x,y= " & x & "," & y, vbokonly
      y = Picture1.height ' force exit of the row loop
      exit for
    end if
  next x
next y


Expert Comment

ID: 6296575

Here's a file over the net for you:


Description: I just made a couple changes to this.I am new at programming so this is my first shot so i hope i don't blow it:) This program lets you open a picture file and it tells you the height and width of the picture in pixels. I think this would come in very handy in making webpages so you'll know the exact dimensions of the pic. If it is really useless let me know. Thx

That's it!

glass cookie : )

Expert Comment

ID: 6297083
Note about rspahitz's code. Change the picbox's scalemode to pixels. It'll run about 225 (15x15) times faster that way. Also, you'll need a backwards loop to search up from the bottom. Same code, but with two changes:

for y=Picture1.height to 0 step -1

     y = 0 ' force exit of the row loop

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Expert Comment

ID: 6297088
To get the width, just pick a row (second parameter of Point) to select points from and search across (inner For-Next loop). Then do the same on the same row but look backwards from the other end.
LVL 22

Expert Comment

ID: 6299282
Thanks, KDivad, I forgot about the "bottom" and "right" request.

Author Comment

ID: 6299479
Wow works like a charm thanks guys!

Kdivad thnaks additionally for your extra help, went so much faster with your "tweaks".  If you want some points I can put then on a sperate question just ask me.

Expert Comment

ID: 6299608
We all have to forget something sometimes. Gives the rest of us a chance to brag a bit. <grin>

Don't worry about it. I may need your help someday.


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