How do you square an uploaded photo without padding with white space, in C#?

Question

In my site, users can upload photos. I currently compress and resize the photo to make sure they aren't huge files. But this creates photos that are of varying dimensions... which makes the site a bit "ugly" in my opinion.

I'd like to ensure the thumbnails are square images, but not by using padding. It's ok if there is some loss of the photo in the thumbnail. I'd like to keep the fidelity of the photo high, even if it means some cropping needs to occur.

Answer 1

Rather than cropping, I would make the div or whatever you put them in a fixed square size. Scale the image to fit inside that square.

How would you decide to crop it? From the top-left? Bottom-right? Center?

Answer 2

I would imagine you need to take the shortest dimension (either w or h), and use that as your dimension for creating the cropped image, essentially you can crop and then scale the image. Check out this article as an example for cropping an image. Also check out this Stack Overflow question regarding image quality.

Answer 3

To make a rectangle into a square you need to either pad, resize without preserving aspect ratio or crop (or combinations).

Here's some code for cropping

http://snippets.dzone.com/posts/show/1484

(I work for Atalasoft -- in our DotImage Photo SDK), it's

AtalaImage img = new AtalaImage("filename.jpg");
AtalaImage img2 = new CropCommand( /*point and size of crop */).Apply(img).Image;
img2.Save("filename", new JpegEncoder(quality), null);

Answer 4

I wrote some code to do this exact thing. I chose to crop it because resizing without preserving aspect ratio looks pretty horrible. I do a crop then a resize to create a thumnail image:

  public Bitmap CreateThumbnail(Bitmap RawImage)
    {
        int width = RawImage.Width;
        int height = RawImage.Height;

        Size ThumbnailDimensions = new Size();
        ThumbnailDimensions.Width = 100;
        ThumbnailDimensions.Height = 100;

        Rectangle cropArea = new Rectangle();
        if (width > height)
        {               
            cropArea.Width = height;
            cropArea.Height = height;
            cropArea.X = 0;
            cropArea.Y = 0;                
        }
        else if (width < height)
        {
            cropArea.Width = width;
            cropArea.Height = width;
            cropArea.X = 0;
            cropArea.Y = 0;
        }
        if(width != height) Bitmap thumbnail = CropImage(RawImage, cropArea);

        thumbnail = ResizeImage(thumbnail, ThumbnailDimensions);
        return thumbnail;
    }

This just crops from the top left corner then resizes it to my thumbnail dimensions.