Image resize?

[Odin13]

Hi

I am still a beginner in this, so sorry if it is a silly question.
In my project I need to change the size of an image (which btw, is in a picturebox) but I can't manage to simply change the width and height of it like I did with the picturebox or some buttons.

I would like something that would do something similar to:

' x is a variable, eg. 500
picturebox1.image.width=x*0.5
picturebox1.image.height=x*0.4

Is there any command to do this?

[dunfiddlin]

Nope. If you want to resize an image in a picturebox you have to resize the box (and use the appropriate SizeMode of course). The control is designed for display only, not graphic manipulation.

[jmcilhinney]

You can't change the size of an existing Image. What you need to do is create a new Bitmap object of the desired size, create a Grpahics object from that and then use the Graphics to draw the original Image onto the new Bitmap. There are lots of examples of that already on the web. I just searched Bing for vb.net resize image and the first three matches, which were the only ones I looked at, all demonstrate this technique. That just shows that you should always be searching the web first. Forums are great for the hard questions but this is not one of the hard questions.

http://www.bing.com/search?q=vb.net+resize+image

[jmcilhinney]

Nope. If you want to resize an image in a picturebox you have to resize the box (and use the appropriate SizeMode of course). The control is designed for display only, not graphic manipulation.

Good point. I was concentrating on the size of the Image itself. Depending on the SizeMode of the PictureBox, resizing the PictureBox will change what the user sees of the Image without changing the Image itself. One issue with that is the quality of the resized image.

If you actually want an Image with a different size then use the technique I mentioned.

[boops boops]

I agree, the PictureBox SizeMode property is the first thing you need to learn. It applies to the Image. The BackgroundImageLayout property applies to the BackgroundImage but can also be useful (for example for tiling).

But to make a new Image with a different size, for most purposes it only takes a single statement:

Dim resizedImage As New Bitmap(sourceImage, width, height)

The more complicated methods involving redrawing the image are useful when you want to enlarge the original with a higher quality than default. In that case you can use DrawImage in combination with one of the high quality Interpolation modes, Bilinear or Bicubic. Which of these looks best depends on the image itself. Bilinear can preserve linear detail better, but otherwise Bicubic is preferable. The low-quality modes can also be useful, for example NearestNeighbor (which enlarges each pixel as a square block and is also faster than anything else).

BB

[jmcilhinney]

I agree, the PictureBox SizeMode property is the first thing you need to learn. It applies to the Image. The BackgroundImageLayout property applies to the BackgroundImage but can also be useful (for example for tiling).

But to make a new Image with a different size, for most purposes it only takes a single statement:

Dim resizedImage As New Bitmap(sourceImage, width, height)

The more complicated methods involving redrawing the image are useful when you want to enlarge the original with a higher quality than default. In that case you can use DrawImage in combination with one of the high quality Interpolation modes, Bilinear or Bicubic. Which of these looks best depends on the image itself. Bilinear can preserve linear detail better, but otherwise Bicubic is preferable. The low-quality modes can also be useful, for example NearestNeighbor (which enlarges each pixel as a square block and is also faster than anything else).

BB

I've never actually tried to do this for myself so I've never researched it thoroughly and I was therefore unaware of that constructor. I learned something new.

[dunfiddlin]

PictureBox1.Image = New Bitmap(PictureBox1.Image, 20, 20)

Make me out to be a liar then. See if I care!

PictureBox1.Image = New Bitmap(PictureBox1.Image, 50, 50)

Image resized in its own picture box!

[boops boops]

Make me out to be a liar then. See if I care!

PictureBox1.Image = New Bitmap(PictureBox1.Image, 50, 50)

Image resized in its own picture box!

Whenever you declare something is impossible, we can be sure it means there is an easy way to do it. (I tried to +rep but it's too soon!)