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Asked: 2026-05-10T15:29:03+00:00

C# question (.net 3.5). I have a class, ImageData, that has a field ushort[,]

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C# question (.net 3.5). I have a class, ImageData, that has a field ushort[,] pixels. I am dealing with proprietary image formats. The ImageData class takes a file location in the constructor, then switches on file extension to determine how to decode. In several of the image files, there is a ‘bit depth’ field in the header. After I decode the header I read the pixel values into the ‘pixels’ array. So far I have not had more than 16bpp, so I’m okay. But what if I have 32bpp?

What I want to do is have the type of pixels be determined at runtime. I want to do this after I read the bit depth out of the header and before I copy the pixel data into memory. Any ideas?

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  1. To boil down your problem, you want to be able to have a class that has a ushort[,] pixels field (16-bits per pixel) sometimes and a uint32[,] pixels field (32-bits per pixel) some other times. There are a couple different ways to achieve this.

    You could create replacements for ushort / uint32 by making a Pixel class with 32-bit and 16-bit sub-classes, overriding various operators up the wazoo, but this incurs a lot of overhead, is tricky to get right and even trickier to determine if its right. Alternately you could create proxy classes for your pixel data (which would contain the ushort[,] or uint32[,] arrays and would have all the necessary accessors to be useful). The downside there is that you would likely end up with a lot of special case code in the ImageData class which executed one way or the other depending on some 16-bit/32-bit mode flag.

    The better solution, I think, would be to sub-class ImageData into 16-bit and 32-bit classes, and use a factory method to create instances. E.g. ImageData is the base class, ImageData16bpp and ImageData32bpp are sub-classes, static method ImageData.Create(string imageFilename) is the factory method which creates either ImageData16bpp or ImageData32bpp depending on the header data. For example:

    public static ImageData Create(string imageFilename) {    // ...    ImageDataHeader imageHeader = ParseHeader(imageFilename);    ImageData newImageData;    if (imageHeader.bpp == 32)    {       newImageData = new ImageData32(imageFilename, imageHeader);    }    else    {       newImageData = new ImageData16(imageFilename, imageHeader);    }    // ...    return newImageData; }
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