Image Resize And Upload With Dynamic Width And Height Values

This blog explains how to resize a given image and save using ASP.NET C# and VB.

We know how to upload an image but in this example, we will supply the width and height values (in pixels) while uploading the image.

Step 1 - Index.aspx page

This is a form with the File Upload control, textboxes for width and height, validation controls, and a button control to handle the events to upload an image.

<fieldset>
     <legend>Image Resize and Save</legend>
         <table>
              <tr>
                        <td><label>Upload Image:</label></td>
                        <td><asp:FileUpload runat="server" ID="fupImage" /></td>
                        <td><asp:RequiredFieldValidator ID="RequiredFieldValidator1" ControlToValidate="fupImage" Display="Dynamic" ForeColor="Red" Font-Size="Small" runat="server" ErrorMessage="Required"></asp:RequiredFieldValidator>
                            <asp:RegularExpressionValidator ID="RegularExpressionValidator1" ValidationExpression="([a-zA-Z0-9\s_\\.\-:])+(.jpg|.jpeg|.gif|.png)$" ControlToValidate="fupImage" runat="server" ForeColor="Red" ErrorMessage="Only jpg, png and gif formats allowed." Display="Dynamic" />
                        </td>
                    </tr>
                    <tr>
                        <td><label>Image Width:</label></td>
                        <td><asp:TextBox ID="txtWidth" runat="server" placeholder="Enter width" onkeypress='return event.charCode >= 48 && event.charCode <= 57'></asp:TextBox>
                        </td>
                        <td>
                            <asp:RequiredFieldValidator ID="RequiredFieldValidator2" ControlToValidate="txtWidth" Display="Dynamic" ForeColor="Red" Font-Size="Small" runat="server" ErrorMessage="Required"></asp:RequiredFieldValidator>
                        </td>
                    </tr>
                    <tr>
                        <td>
                            <label>Image Height:</label></td>
                        <td>
                            <asp:TextBox ID="txtHeight" runat="server" placeholder="Enter Height" onkeypress='return event.charCode >= 48 && event.charCode <= 57'></asp:TextBox>
                        </td>
                        <td>
                            <asp:RequiredFieldValidator ID="RequiredFieldValidator3" runat="server" ControlToValidate="txtHeight" Display="Dynamic" ForeColor="Red" Font-Size="Small" ErrorMessage="Required"></asp:RequiredFieldValidator>
                        </td>
                    </tr>
                    <tr>
                        <td></td>
                        <td>
                            <asp:Button runat="server" ID="btnUpload" Text="Resize & Upload" OnClick="btnUpload_Click" />
                        </td>
                    </tr>
                    <tr>
                        <td colspan="3">
                            <asp:Label runat="server" ID="lblResult" ForeColor="Red" Font-Size="Small" Font-Bold="true"></asp:Label></td>
                    </tr>
                </table>
            </fieldset>

Step 2 - Index.aspx.cs file

Here is the C# code snippet for image resizing with dynamic width and height values on a button-click event.

protected void btnUpload_Click(object sender, EventArgs e)
        {
            string newFile = string.Empty;
            if (fupImage.HasFile)
            {
                int width = Convert.ToInt32(txtWidth.Text);
                int height = Convert.ToInt32(txtHeight.Text);
                Stream inp_Stream = fupImage.PostedFile.InputStream;
                using (var image = System.Drawing.Image.FromStream(inp_Stream))
                {
                    Bitmap myImg = new Bitmap(width, height);
                    Graphics myImgGraph = Graphics.FromImage(myImg);
                    myImgGraph.CompositingQuality = CompositingQuality.HighQuality;
                    myImgGraph.SmoothingMode = SmoothingMode.HighQuality;
                    myImgGraph.InterpolationMode = InterpolationMode.HighQualityBicubic;
                    var imgRectangle = new Rectangle(0, 0, width, height);
                    myImgGraph.DrawImage(image, imgRectangle);
                    string ext = string.Empty;
                    ext = System.IO.Path.GetExtension(fupImage.FileName.ToString()).ToLower();
                    newFile = DateTime.Now.ToString("ddMMyyyyhhmmsstt") + "_" + width + "X" + height + ext;
                    // Save the file
                    var path = Path.Combine(Server.MapPath("~/ResizedImages"), newFile);
                    myImg.Save(path, image.RawFormat);
                    lblResult.Text = "Image resized and saved in folder 'ResizedImages' successfully";
                    lblResult.ForeColor = Color.Green;
                    txtWidth.Text = txtHeight.Text = "";
                }
            }
            else
            {
                lblResult.Text = "please upload image";
            }
        }

Here is the VB code snippet for image resize with given width and height values on the button-click event.

Index.aspx.vb file

Protected Sub btnUpload_Click(sender As Object, e As EventArgs) Handles btnUpload.Click
        Dim newFile As String = String.Empty
        If (fupImage.HasFile) Then
            Dim width As Integer = txtWidth.Text
            Dim height As Integer = txtHeight.Text
            Dim inp_Stream As Stream = fupImage.PostedFile.InputStream
            Using image = System.Drawing.Image.FromStream(inp_Stream)
                Dim myImg As Bitmap = New Bitmap(width, height)
                Dim myImgGraph As Graphics = Graphics.FromImage(myImg)
                myImgGraph.CompositingQuality = CompositingQuality.HighQuality
                myImgGraph.SmoothingMode = SmoothingMode.HighQuality
                myImgGraph.InterpolationMode = InterpolationMode.HighQualityBicubic
                Dim imgRectangle = New Rectangle(0, 0, width, height)
                myImgGraph.DrawImage(image, imgRectangle)
                Dim ext As String = String.Empty
                ext = System.IO.Path.GetExtension(fupImage.FileName.ToString()).ToLower()
                newFile = DateTime.Now.ToString("ddMMyyyyhhmmsstt") & "_" & width & "X" & height & ext
                Dim path = System.IO.Path.Combine(Server.MapPath("~/ResizedImages"), newFile)
                myImg.Save(path, image.RawFormat)
                lblResult.Text = "Image resized and saved in folder 'ResizedImages' successfully"
                lblResult.ForeColor = Color.Green
                txtWidth.Text = String.Empty
                txtHeight.Text = String.Empty
            End Using
        Else
            lblResult.Text = "Please upload image"
        End If
    End Sub

Run the page in the browser to see results.

 

Upload an image and pass the desired width, height values. Hit the "Resize and Upload" button to see the results. Open the ‘ResizedImages’ folder in your project.

 

Hurray, the image is resized successfully in the desired dimensions. 

Summary

In this article, I discussed how to resize the image using the Stream class. It can be useful if we need different dimensions for images to be uploaded on our website. Here, we passed dynamic values for width and height. If we want the image to be of a particular dimension, we can make it statically from the code behind.