Saving an Image in vb.net

[spathma]

Hi,

I'm trying to save an image from a picturebox which contains a live webcam feed using the following line in a button,

pictureBox1.image.Save("data.jpg", System.Drawing.Imaging.ImageFormat.Jpeg)

but when I run this, I keep getting an error saying "Object reference not set to an instance of an object"..how can I can fix this problem??

Thx,

[nemaroller]

I don't understand how you are actually able to run a webcam video through a picturebox, but by the looks of that error..

the picturebox does not actually contain the image data... so when you try to save the contents of its image property as you did above, there is nothing there, so it reports no object available.

[nemaroller]

In other words, you are probably implementing the webcam video by drawing on picturebox's graphics surface, which does not mean the picturebox contains the image. It simply means you are overriding what the picturebox would normally draw on its surface (the image contained in its image property).

[spathma]

so can I get a hold of the webcam data from the picturebox??

[nemaroller]

Do you have the code you use to put the webcam data there?

[MrPolite]

just a suggestion, I dont have any idea whatsoever on what's going on... but as nemaroller said the picturebox.Image is probably null.... if you are drawing the stuff on the picturebox manually then I guess this would apply to you:
instead of using the graphics object passed in the paint event of the picturebox (of instead of calling picturebox.CreateGraphics) try to do something like this

dim gr as graphics = graphics.fromImage (yourPictureBox.Image)
'now when you call 'gr' it modifies the actual image in the picturebox

dunno if I'm helping, but thought I should mention it

[spathma]

I followed a tutorial from the following site to implement the live web cam feed..

http://www.webtropy.com/articles/art7.asp

[nemaroller]

Ok, that code is what i suspected.

The image data does not reside inside the picturebox image property. The code is simply drawing on the picturebox's graphics surface. The picturebox isn't drawing the image, the VFW (Video For Windows) API is, therefore the picturebox knows nothing about what's being displayed.

There is no way to 'capture' the image using Picturebox methods.

However I suspect the VFW API may have a way to snapshot the image data, and fill a byte array or buffer with it.

[scuzymoto]

I don't know if you're interested in third party tools but...

I use an activeX add-in that I purchased from http://www.activevideotools.com for under a hundred bucks that made the task of capturing still photos from an incoming video feed extremely easy.

Im using a winnov videum capture card but any video card that supports VFW will work.