How to resize image with VB.NET

1. Private Sub btnScale_Click(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles btnScale.Click
' Get the scale factor.
Dim scale_factor As Single = Single.Parse(txtScale.Text)
' Get the source bitmap.
Dim bm_source As New Bitmap(picSource.Image)
' Make a bitmap for the result.
Dim bm_dest As New Bitmap( _
CInt(bm_source.Width * scale_factor), _
CInt(bm_source.Height * scale_factor))
' Make a Graphics object for the result Bitmap.
Dim gr_dest As Graphics = Graphics.FromImage(bm_dest)
' Copy the source image into the destination bitmap.
gr_dest.DrawImage(bm_source, 0, 0, _
bm_dest.Width + 1, _
bm_dest.Height + 1)
' Display the result.
picDest.Image = bm_dest
End Sub
Public Shared Function ResizeImage(ByVal InputImage As Image) As Image
Return New Bitmap(InputImage, New Size(64, 64))
End Function
Where;
1. "InputImage" is the image you want to resize.
2. "64 X 64" is the required size you may change it as your needs i.e 32X32 etc.
#Region " ResizeImage "

2. Public Overloads Shared Function ResizeImage(SourceImage As
Drawing.Image, TargetWidth As Int32, TargetHeight As Int32) As Drawing.Bitmap
Dim bmSource = New Drawing.Bitmap(SourceImage)
Return ResizeImage(bmSource, TargetWidth, TargetHeight)
End Function
Public Overloads Shared Function ResizeImage(bmSource As Drawing.Bitmap,
TargetWidth As Int32, TargetHeight As Int32) As Drawing.Bitmap
Dim bmDest As New Drawing.Bitmap(TargetWidth, TargetHeight,
Drawing.Imaging.PixelFormat.Format32bppArgb)
Dim nSourceAspectRatio = bmSource.Width / bmSource.Height
Dim nDestAspectRatio = bmDest.Width / bmDest.Height
Dim NewX = 0
Dim NewY = 0
Dim NewWidth = bmDest.Width
Dim NewHeight = bmDest.Height
If nDestAspectRatio = nSourceAspectRatio Then
'same ratio
ElseIf nDestAspectRatio > nSourceAspectRatio Then
'Source is taller
NewWidth = Convert.ToInt32(Math.Floor(nSourceAspectRatio *
NewHeight))
NewX = Convert.ToInt32(Math.Floor((bmDest.Width - NewWidth) / 2))
Else
'Source is wider
NewHeight = Convert.ToInt32(Math.Floor((1 / nSourceAspectRatio) *
NewWidth))
NewY = Convert.ToInt32(Math.Floor((bmDest.Height - NewHeight) /
2))
End If
Using grDest = Drawing.Graphics.FromImage(bmDest)
With grDest
.CompositingQuality =
Drawing.Drawing2D.CompositingQuality.HighQuality
.InterpolationMode =
Drawing.Drawing2D.InterpolationMode.HighQualityBicubic
.PixelOffsetMode =
Drawing.Drawing2D.PixelOffsetMode.HighQuality
.SmoothingMode = Drawing.Drawing2D.SmoothingMode.AntiAlias
.CompositingMode =
Drawing.Drawing2D.CompositingMode.SourceOver
.DrawImage(bmSource, NewX, NewY, NewWidth, NewHeight)
End With
End Using
Return bmDest
End Function
#End Region

3. Dim source As New Bitmap("C:image.png")
Dim target As New Bitmap(size.Width, size.Height, PixelFormat.Format24bppRgb)
Using graphics As Graphics = Graphics.FromImage(target)
graphics.DrawImage(source, new Size(48, 48))
End Using
Dim x As Integer = 0
Dim y As Integer = 0
Dim k = 0
Dim l = 0
Dim bm As New Bitmap(p1.Image)
Dim om As New Bitmap(p1.Image.Width, p1.Image.Height)
Dim r, g, b As Byte
Do While x < bm.Width - 1
y = 0
l = 0
Do While y < bm.Height - 1
r = 255 - bm.GetPixel(x, y).R
g = 255 - bm.GetPixel(x, y).G
b = 255 - bm.GetPixel(x, y).B
om.SetPixel(k, l, Color.FromArgb(r, g, b))
y += 3
l += 1
Loop
x += 3
k += 1
Loop
p2.Image = om

4. Private Sub btnScale_Click(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles btnScale.Click
' Get the scale factor.
Dim scale_factor As Single = Single.Parse(txtScale.Text)
' Get the source bitmap.
Dim bm_source As New Bitmap(picSource.Image)
' Make a bitmap for the result.
Dim bm_dest As New Bitmap( _
CInt(bm_source.Width * scale_factor), _
CInt(bm_source.Height * scale_factor))
' Make a Graphics object for the result Bitmap.
Dim gr_dest As Graphics = Graphics.FromImage(bm_dest)
' Copy the source image into the destination bitmap.
gr_dest.DrawImage(bm_source, 0, 0, _
bm_dest.Width + 1, _
bm_dest.Height + 1)
' Display the result.
picDest.Image = bm_dest
End Sub
Resizing images with Visual Basic (VB6) and
csXImage
Here are some code fragments showing how to use the ActiveX control csXImage to resize
images. The code is written in Visual Basic (VB 6). It is assumed that you have already installed
either the full or trial version of csXImage and have added a control to a form in Visual Basic.
More on getting started with csXImage in VB.
The ResizeImage method
The ResizeImage method will resize the image that is loaded in the control by specifying a new
width and height. If both parameters are given a non zero value, the new image will have exactly
those dimensions. This can lead to the image losing its aspect ratio. Sometimes it is necessary to
change the aspect ratio, for example with a faxed image that has different pixel densities in the X
and Y directions.
The following code produces an image that is 640 x 480 pixels regardless of its original size.
ImageBox1.ResizeImage 640, 480

5. If either the width or height parameter of the ResizeImage method is zero, the new image will be
resized to the width or height that is specified and will maintain the aspect ratio.
The following code will produce an image that is 200 pixels wide and it will maintain the aspect
ratio. The final height will vary depending on the original height. Note that the new image will
always be 200 pixels wide even if it was smaller to start with.
ImageBox1.ResizeImage 200, 0
The ResizeFit method
The ResizeFit method also takes a width and height parameter but it will always maintain aspect
ratio and it will never enlarge an image. The new image will always fit into the size defined by
the parameters.
The following code will resize the image to fit inside a box measuring 200 pixels wide by 100
pixels high. An image with dimensions 300 x 200 will be resized to 150 x 100 but an image that
is 500 x 200 will be resized to 200 x 80 pixels.
ImageBox1.ResizeFit 200, 100
The ScaleImage method
The ScaleImage method takes a single parameter which is the percentage scaling that will be
applied. 100 would cause no change, 50 would reduce the image to half the width and half the
height. 200 would double the width and height. For example:
ImageBox1.ScaleImage 50
When an image is resized with csXImage, any supported meta data will be preserved, including
IPTC, EXIF and ICC colour profiles. This meta data can be removed if required.
The resized image will appear smoother if it is a 24 bit image. That is, if the ColorFormat
property is set to cf24bit. If the resized image contains jagged edges, the Resample property
could be set before the resize. This gives a smoother image but it can lose detail, especially small
text. When using Resample set the FilterType property as well.

6. Mengubah ukuran Gambar di VB.NET
Saya ingin membuat utilitas VB sederhana untuk mengubah ukuran gambar menggunakan
vb.net. Saya mengalami kesulitan mencari tahu kelas vb apa yang digunakan untuk benar-benar
memanipulasi gambar. Kelas Gambar dan kelas Bitmap tidak berfungsi.
Setiap ide, petunjuk, kiat, tautan tutorial sangat dihargai.
Terima kasih.
vb.netimageresizeimage-manipulation
12
27 Jan 2010Moshe
Berikut ini adalah artikel dengan rincian lengkap tentang cara melakukan ini.
Private Sub btnScale_Click(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles btnScale.Click
' Get the scale factor.
Dim scale_factor As Single = Single.Parse(txtScale.Text)
' Get the source bitmap.
Dim bm_source As New Bitmap(picSource.Image)
' Make a bitmap for the result.
Dim bm_dest As New Bitmap( _
CInt(bm_source.Width * scale_factor), _
CInt(bm_source.Height * scale_factor))
' Make a Graphics object for the result Bitmap.
Dim gr_dest As Graphics = Graphics.FromImage(bm_dest)
' Copy the source image into the destination bitmap.
gr_dest.DrawImage(bm_source, 0, 0, _
bm_dest.Width + 1, _
bm_dest.Height + 1)
' Display the result.
picDest.Image = bm_dest
End Sub
[Sunting]
Satu lagi pada baris yang sama.
14
27 Jan 2010
Binoj Antony

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Anda cukup menggunakan kode satu baris ini untuk mengubah ukuran gambar Anda dalam
visual basic .net
Public Shared Function ResizeImage(ByVal InputImage As Image) As Image
Return New Bitmap(InputImage, New Size(64, 64))
End Function
Dimana;
1. "InputImage"adalahgambaryanginginAndaubahukurannya.
2. "64 X 64" adalahukuran yangdiperlukan,Andadapatmengubahnyasesuaikebutuhan,mis.
32X32 dll.
16
18 Mar 2014
MuhammadSaqib
Ini akan mengubah ukuran gambar apa pun menggunakan kualitas terbaik dengan dukungan
untuk 32bpp dengan alpha. Gambar baru akan memiliki gambar asli berpusat di dalam yang baru
dengan rasio aspek asli.
#Region " ResizeImage "
Public Overloads Shared Function ResizeImage(SourceImage As
Drawing.Image, TargetWidth As Int32, TargetHeight As Int32) As Drawing.Bitmap
Dim bmSource = New Drawing.Bitmap(SourceImage)
Return ResizeImage(bmSource, TargetWidth, TargetHeight)
End Function
Public Overloads Shared Function ResizeImage(bmSource As Drawing.Bitmap,
TargetWidth As Int32, TargetHeight As Int32) As Drawing.Bitmap
Dim bmDest As New Drawing.Bitmap(TargetWidth, TargetHeight,
Drawing.Imaging.PixelFormat.Format32bppArgb)
Dim nSourceAspectRatio = bmSource.Width / bmSource.Height
Dim nDestAspectRatio = bmDest.Width / bmDest.Height

8. Dim NewX = 0
Dim NewY = 0
Dim NewWidth = bmDest.Width
Dim NewHeight = bmDest.Height
If nDestAspectRatio = nSourceAspectRatio Then
'same ratio
ElseIf nDestAspectRatio > nSourceAspectRatio Then
'Source is taller
NewWidth = Convert.ToInt32(Math.Floor(nSourceAspectRatio *
NewHeight))
NewX = Convert.ToInt32(Math.Floor((bmDest.Width - NewWidth) / 2))
Else
'Source is wider
NewHeight = Convert.ToInt32(Math.Floor((1 / nSourceAspectRatio) *
NewWidth))
NewY = Convert.ToInt32(Math.Floor((bmDest.Height - NewHeight) /
2))
End If
Using grDest = Drawing.Graphics.FromImage(bmDest)
With grDest
.CompositingQuality =
Drawing.Drawing2D.CompositingQuality.HighQuality
.InterpolationMode =
Drawing.Drawing2D.InterpolationMode.HighQualityBicubic
.PixelOffsetMode =
Drawing.Drawing2D.PixelOffsetMode.HighQuality
.SmoothingMode = Drawing.Drawing2D.SmoothingMode.AntiAlias
.CompositingMode =
Drawing.Drawing2D.CompositingMode.SourceOver
.DrawImage(bmSource, NewX, NewY, NewWidth, NewHeight)
End With
End Using
Return bmDest
End Function
#End Region
4
11 Mar 2013
Carter Medlin
Tidak tahu banyak sintaks VB.NET tapi di sini dan idenya
Dim source As New Bitmap("C:image.png")
Dim target As New Bitmap(size.Width, size.Height, PixelFormat.Format24bppRgb)
Using graphics As Graphics = Graphics.FromImage(target)
graphics.DrawImage(source, new Size(48, 48))
End Using
2
27 Jan 2010

9. Alex LE
Dim x As Integer = 0
Dim y As Integer = 0
Dim k = 0
Dim l = 0
Dim bm As New Bitmap(p1.Image)
Dim om As New Bitmap(p1.Image.Width, p1.Image.Height)
Dim r, g, b As Byte
Do While x < bm.Width - 1
y = 0
l = 0
Do While y < bm.Height - 1
r = 255 - bm.GetPixel(x, y).R
g = 255 - bm.GetPixel(x, y).G
b = 255 - bm.GetPixel(x, y).B
om.SetPixel(k, l, Color.FromArgb(r, g, b))
y += 3
l += 1
Loop
x += 3
k += 1
Loop
p2.Image = om

10. Public Sub AutosizeImage(ByVal ImagePath As String, ByVal picBox As
PictureBox, Optional ByVal pSizeMode As PictureBoxSizeMode =
PictureBoxSizeMode.CenterImage)
Try
picBox.Image = Nothing
picBox.SizeMode = pSizeMode
If System.IO.File.Exists(ImagePath) Then
Dim imgOrg As Bitmap
Dim imgShow As Bitmap
Dim g As Graphics
Dim divideBy, divideByH, divideByW As Double
imgOrg = DirectCast(Bitmap.FromFile(ImagePath), Bitmap)
divideByW = imgOrg.Width / picBox.Width
divideByH = imgOrg.Height / picBox.Height
If divideByW > 1 Or divideByH > 1 Then
If divideByW > divideByH Then
divideBy = divideByW
Else
divideBy = divideByH
End If
imgShow = New Bitmap(CInt(CDbl(imgOrg.Width) / divideBy),
CInt(CDbl(imgOrg.Height) / divideBy))
imgShow.SetResolution(imgOrg.HorizontalResolution,
imgOrg.VerticalResolution)
g = Graphics.FromImage(imgShow)
g.InterpolationMode =
Drawing2D.InterpolationMode.HighQualityBicubic
g.DrawImage(imgOrg, New Rectangle(0, 0,
CInt(CDbl(imgOrg.Width) / divideBy), CInt(CDbl(imgOrg.Height) / divideBy)),
0, 0, imgOrg.Width, imgOrg.Height, GraphicsUnit.Pixel)
g.Dispose()
Else
imgShow = New Bitmap(imgOrg.Width, imgOrg.Height)
imgShow.SetResolution(imgOrg.HorizontalResolution,
imgOrg.VerticalResolution)
g = Graphics.FromImage(imgShow)
g.InterpolationMode =
Drawing2D.InterpolationMode.HighQualityBicubic
g.DrawImage(imgOrg, New Rectangle(0, 0, imgOrg.Width,
imgOrg.Height), 0, 0, imgOrg.Width, imgOrg.Height, GraphicsUnit.Pixel)
g.Dispose()
End If
imgOrg.Dispose()
picBox.Image = imgShow
Else
picBox.Image = Nothing
End If
Catch ex As Exception
MsgBox(ex.ToString)
End Try
End Sub

11. This chapter is from the book
Visual BasicProgrammer'sGuide tothe .NET FrameworkClassLibrary
Learn More Buy
This chapter is from the book
Visual BasicProgrammer'sGuide tothe .NET FrameworkClassLibrary
Learn More Buy
Working with Images
In this section, you will see how to use two of the most common graphic types a programmer
interacts with: bitmaps and icons. As stated earlier in the chapter, all user-interface objects in
Windows are some form of a bitmap; a bitmap is simply a collection of pixels set to various
colors.
Images
The namespace library gives us three classes for working with images: Image, Bitmap and Icon.
Image is simply the base class from which the others inherit. Bitmap allows us to convert a
graphics file into the native GDI+ format (bitmap). This class can be used to define images as fill
patterns, transform images for display, define the look of a button—its uses are many. Although
the bitmap format is used to manipulate images at the pixel level, GDI+ can actually work with
the following image types:
 Bitmaps (BMP)
 Graphics Interchange Format (GIF)
 Joint Photographic Experts Group (JPEG)
 Exchangeable Image File (EXIF)
 Portable Network Graphics (PNG)
 Tag Image File Format (TIFF)
Creating an instance of Bitmap requires a filename, stream, or another valid Image instance. For
example, the following line of code will instantiate a Bitmap object based on a JPEG file:
Dim myBitmap As New System.Drawing.Bitmap(fileName:="Sample.jpg")

12. Once instantiated, we can do a number of things with the image. For instance, we can change its
resolution with the SetResolution method or make part of the image transparent with
MakeTransparent. Of course, we will also want to draw our image to the form. We use the
DrawImage method of the Graphics class to output the image to the screen. The DrawImage
method has over 30 overloaded parameter sets. In its simplest form, we pass the method an
instance of Bitmap and the upper-left coordinate of where we want the method to begin drawing.
For example:
myGraphics.DrawImage(image:=myBitmap, point:=New Point(x:=5, y:=5))
Scaling and Cropping
It is often helpful to be able to scale or crop an image to a different size. Suppose you need a 100
x 100 image to fit in a 20 x 20 space, or you want to give your users the ability to zoom in on a
portion of an image. You use a variation of the DrawImage method to scale images. This
overloaded method takes a Rectangle instance as the destination for drawing your image.
However, if the rectangle is smaller or larger than your image, the method will automatically
scale the image to match the bounds of the rectangle.
Another version of the DrawImage method takes both a source rectangle and a destination
rectangle. The source rectangle defines the portion of the original image to be drawn into the
destination rectangle. This, effectively, is cropping. The source rectangle defines how the image
gets cropped when applied to the destination. Of course, you can crop to the original size or scale
the cropped portion to a new size. Listing 9.8 provides a detailed code example of both scaling
and cropping an image.
Listing 9.8 Scale and Crop
Protected Overrides Sub OnClick(ByVal e As System.EventArgs)
'local scope
Dim myBitmap As System.Drawing.Bitmap
Dim myGraphics As Graphics
Dim mySource As Rectangle
Dim myDestination As Rectangle
'create an instance of bitmap based on a file
myBitmap = New System.Drawing.Bitmap(fileName:="dotnet.gif")
'return the current form as a drawing surface
myGraphics = Graphics.FromHwnd(ActiveForm().Handle)
'define a rectangle as the size of the original image (source)
mySource = New Rectangle(x:=0, y:=0, Width:=81, Height:=45)
'draw the original bitmap to the source rectangle
myGraphics.DrawImage(image:=myBitmap, rect:=mySource)
'create a destination rectangle
myDestination = New Rectangle(x:=90, y:=0, Width:=162, Height:=90)
'output the image to the dest. rectangle (scale)
myGraphics.DrawImage(image:=myBitmap, rect:=myDestination)

13. 'output a cropped portion of the source
myGraphics.DrawImage(image:=myBitmap, _
destRect:=New Rectangle(x:=0, y:=100, Width:=30, Height:=30), _
srcRect:=New Rectangle(x:=0, y:=35, Width:=14, Height:=14), _
srcUnit:=GraphicsUnit.Pixel)
End Sub
Notice that we actually drew the image to the form three times. The first time, we drew the
image into a rectangle (mySource) based on its original size. The second time, we scaled the
image to two times its original size (myDestination) by creating a larger rectangle and
outputting the image accordingly. Finally, we cropped a portion of the original output and put it
in a new, larger rectangle. Figure 9.5 shows the code's output to the form.
Figure 9.5 Scale and crop output.
Icons
An icon in Windows is a small bitmap image that represents an object. You cannot go far in
without seeing and working with icons. For example, the File Explorer uses icons to represent
folders and files; your desktop contains icons for My Computer, Recycle Bin, and My Network
Places.
We use the Icon class to work with icons in .NET. We can instantiate an Icon instance in much
the same way we created Bitmap objects. The following code creates an icon based on a file
name:
Dim myIcon as New Icon(fileName:="myIcon.ico")
The DrawIcon method of the Graphics class is used to draw the icon to the form. To it, you can
pass the icon and either just the upper-left x and y coordinates or a bounding rectangle. If you
pass a Rectangle instance, the icon will be scaled based on the bounding rectangle. The
following line of code draws an icon object into a bounding rectangle.
myGraphics.DrawIcon(icon:=myIcon, _
rectangle:=New Rectangle(x:=5, y:=5, width:=32, height:=32))
The Graphics class also gives us the DrawIconUnstretched method that allows us to specify a
bounding rectangle without actually scaling the icon. In fact, if the icon is larger than the
bounding rectangle, it will be cropped to fit from the left corner down and to the right.
Suggestions for Further Exploration
 To animate images, take a look at the ImageAnimator class.
 Check out the SmoothingMode property of the Graphics class and the SmoothingMode
enumeration members. This method allows you to set things like antialiasing to make
your graphics look "smoother."