Image Dimension Validation

Demo uploads land in a temporary store and are swept after 60 minutes. To keep files, handle FileUploaded — see Single File for the complete save pattern.

Validate image width and height before upload using EnableImageDimensions="true". Set minimum and maximum pixel dimensions with MinImageWidth, MinImageHeight, MaxImageWidth, and MaxImageHeight.

What you should see: images outside 200×200 to 4000×4000 pixels are rejected by reading the image header in the browser - an undersized file never uploads.

Drag & drop files here, or paste from clipboard

<au:AjaxFileUpload ID="Uploader1" runat="server"
 AllowedExtensions=".jpg,.png,.gif,.webp"
 EnableImageDimensions="true"
 MinImageWidth="200"
 MinImageHeight="200"
 MaxImageWidth="4000"
 MaxImageHeight="4000"
 ButtonText="Select Image"
 AutoUpload="true"
 ShowProgress="true" />

Images must be at least 200x200 and no larger than 4000x4000 pixels. Try uploading a small icon or a very large image to see the validation.