如何去除栅格影像的黑边？

IRasterRenderer RR = RL.Renderer; 

IRasterRGBRenderer rasterRGBRenderer = null; 

if (RR is IRasterRGBRenderer) 

rasterRGBRenderer = RR as IRasterRGBRenderer; 

RR.Update(); 

rasterRGBRenderer.RedBandIndex = 0; 

rasterRGBRenderer.GreenBandIndex = 1; 

rasterRGBRenderer.BlueBandIndex = 2; 

IRgbColor rgb = new RgbColorClass(); 

rgb.NullColor = true; 

IRasterStretch2 RS = rasterRGBRenderer as IRasterStretch2; // IRasterStretch无法设置数组，需用2 

double background = 

{ 

0, 0, 0 

}; 

RS.Background = true; 

RS.BackgroundValue = background as object; 

RS.BackgroundColor = rgb as IColor; 

axMapControl1.Refresh();

IRasterRenderer RR = RL.Renderer;

IRasterStretchColorRampRenderer RSC = null;

if (RR is IRasterStretchColorRampRenderer)

RSC = RR as IRasterStretchColorRampRenderer;

RR.Update();

RSC.BandIndex = 0;

IRgbColor rgb = new RgbColorClass(); 

rgb.NullColor = true; 

IRasterStretch RS = RSC as IRasterStretch;

RS.Background = true;

RS.set_BackgroundValues(0);

RS.BackgroundColor = rgb as IColor;

axMapControl1.Refresh();