Converting C# Data Value to ArcObject Raster Pixel Value

The length of remote sensing pixel value is constrained by a predefined pixel value type. It is an unchangeable property for each remote sensing image and saving an unsupported value to a image may cause unpredictable errors like application crash or information loss resulted from implicit data type conversion.

If you are developing application based on ArcObject, you could know the pixel type of a raster layer simply with following code.

IRasterLayer rasterLayer = (IRasterLayer)layer;
IRasterProps rasterProps = (IRasterProps)rasterLayer.Raster;

// Get the pixel type of you raster layer
rstPixelType pixelType = rasterProps.PixelType;

You can find a full list and detailed explanation of ArcObject raster pixel types in this page.

Not every raster pixel types has a corresponding C# value type. So I make a list for those pixels types having relative in C# so that we can make correct conversion while developing.

ArcMap Pixel Type	Description	Corresponding C# Data Type	Supported
PT_UNKNOWN	unknown		No
PT_U1	1 bit		No
PT_U2	2 bit		No
PT_U4	4 bit		No
PT_UCHAR	unsigned 8 bit integer	Byte	Yes
PT_CHAR	8 bit integer	SByte	Yes
PT_USHORT	unsigned 16 bit integer	UInt16	Yes
PT_SHORT	16 bit integer	Int16	Yes
PT_ULONG	unsigned 32 bit integer	UInt32	Yes
PT_LONG	32 bit integer	Int32	Yes
PT_FLOAT	single precision floating point	Single	Yes
PT_DOUBLE	double precision floating point	Double	Yes
PT_COMPLEX	single precision complex		No
PT_DCOMPLEX	double precision complex		No
PT_CSHORT	short integer complex		No
PT_CLONG	long integer complex		No

Based on this table, I write a function to wrap the conversion from C# data type to valid ArcObject pixel value type. I use it in my project ArcMap Raster Edit Suite and it work pretty well.

/// <summary>
/// Convert the csharp value to the ArcObject pixel value.
/// </summary>
/// <param name="csharpValue">Cshapr value</param>
/// <param name="pixelValueType">The pixel type of ouput value</param>
/// <param name="pixelValue">Output pixel value</param>
/// <returns>A value indicating whether the convention is successful</returns>
public static bool CSharpValue2PixelValue(object csharpValue, rstPixelType pixelValueType, out object pixelValue)
{
    try
    {
        switch (pixelValueType)
        {
            case rstPixelType.PT_UCHAR:
                pixelValue = (object)Convert.ToByte(csharpValue);
                return true;
            case rstPixelType.PT_CHAR:
                pixelValue = (object)Convert.ToSByte(csharpValue);
                return true;
            case rstPixelType.PT_SHORT:
                pixelValue = (object)Convert.ToInt16(csharpValue);
                return true;
            case rstPixelType.PT_USHORT:
                pixelValue = (object)Convert.ToUInt16(csharpValue);
                return true;
            case rstPixelType.PT_CLONG:
                pixelValue = (object)Convert.ToInt32(csharpValue);
                return true;
            case rstPixelType.PT_ULONG:
                pixelValue = (object)Convert.ToUInt32(csharpValue);
                return true;
            case rstPixelType.PT_FLOAT:
                pixelValue = (object)Convert.ToSingle(csharpValue);
                return true;
            case rstPixelType.PT_DOUBLE:
                pixelValue = (object)Convert.ToDouble(csharpValue);
                return true;
            default:
                pixelValue = null;
                return false;
        }
    }
    catch (Exception)
    {
        pixelValue = null;
        return false;
    }
}