Frequently asked questions

If you're getting an error message, see the troubleshooting page instead.

Q: Is it possible to specify the width and height, and have your image resized and cropped to fit the aspect ratio, losing as little image area as possible?: A: Yes, and it is easy. Use ?width=x&height=y&mode=crop.
Q: Are multi-page .TIFFs supported?: A: Yes - you can convert any page of a multi-page .TIFF to .jpg, .png, or .gif. Use ?page=x&format=jpg
Q: Can I resize the same image to different sizes?: A: Yes - there is no limit on how many sizes of an image can be created.
Q: Is load balancing across multiple servers supported?: A: Yes, and all plugins support web farms, web gardens, and load balancing.
Q: Do the image names change when they are resized? Is SEO affected?: A: No, image names are retained - SEO isn't affected.
Q: If I resize a photo to its original size, will a new photo be returned, or the original?: A: All photos are re-compressed, even if the original photo is the same size. This allows ICC correction, file size improvement, and metadata removal.
Q: Can the resizer both crop, then resize at the same time?: A: Yes, you can specify a crop rectangle with ?crop=(x1,y1,x2,y2) or ?mode=crop, and add &width=x or any of the resizing commands to resizing the resulting crop. All commands can be combined.
Q: Can I use this on images not located on the server?: A: Yes, with RemoteReader (Any HTTP server), S3Reader (Amazon S3 blobs), AzureReader (Azure blobs), MongoReader (GridFS) or SqlReader (SQL blobs).
Q: When I resize a small image to larger dimensions, it stays at the original size.: A: This is by design - add &scale=both to allow images to be upscaled. You might want to consider up-scaling client-side to save bandwidth... Just set both width and height on the <img> tag. If you just want padding, use &scale=canvas
Q: Can I use this with images stored in a database?: A: Sure, with the SqlReader plugin.
Q: Can I use this to resize images as users upload them?: A: Sure! I suggest keeping the original images around, and using the resizer normally (in case you later want larger images). However, it's easy to [resize during upload](/docs/howto/upload-and-resize).
Q: Is in necessary to wildcard map everything to ASP.NET when using IIS6?: A: No - you can map .jpg, .png, and .gif individually, but you need to follow this KB article to prevent issues.
Q: I asked my hosting company to add the wildcard mapping, but images don't resize when I add ?width=x; they appear in their original size. I've verified that the HttpModule entry is in Web.Config: A: The tech support person didn't add the wildcard mapping correctly. If you can't access /resizer.debug, but you can get to /resizer.debug.ashx, it's not possible that wildcard mapping is enabled. image requests never reach asp.net. Add to your web.config temporarily (never leave it in long on a production site - slows things down). Visit mysite.com/anyimage.jpg Visit mysite.com/trace.axd. If the JPG URL isn't in here, it is impossible that the wildcard mapping is installed correctly.
Q: I'm getting OutOfMemory exceptions when I try to resize certain large images for the first time (subsequent requests are fine). They're only 15MB in jpeg form, and I have 100MB of free RAM.: A: A 15MB JPG uncompresses to about 80MB in bitmap form (depending upon the compression level). If you are resizing to a 2MB jpeg (15MB BMP), memory requirements for the operation are roughly 110MB (15 + 80 + 15). If you plan on using the resizer for very high-resolution photos (above 8MP), I suggest making sure you have ample amounts of RAM. 400MB to 1GB is usually plenty for the average web site with disk caching enabled.