Why my added tif image(RGB) color only has one single color (green)?

when i add tif image, the color is not same as in the arcmap. why? The code by mapwingis 5.3 is below.

The color of added image by up code is below.

And the return value(rrcolorScheme) of .RenderingMode is only read. How to change it to rrRGB

I got the answer :
newImage.AllowGridRendering = tkGridRendering.grNever;
newImage.UseRgbBandMapping = true;