Vajram,<br><br>You should check if the object ct, is null after band.GetRasterColorTable(). Perhaps there is no color table for D:\pr.IMG<br><br><div class="gmail_quote">On Mon, Jul 12, 2010 at 5:37 PM, mail2vajram <span dir="ltr"><<a href="mailto:mail2vajram@gmail.com">mail2vajram@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><br>
i want to know how to read the color value of particular pixel. and<br>
previously i used the following code to read the color table.but now it<br>
throws null reference exception.why?. My objective is to prepare the Rater<br>
legend control based on pixel values.<br>
<br>
<br>
Gdal.AllRegister();<br>
Dataset ds = Gdal.Open(@"D:\pr.IMG", Access.GA_ReadOnly);<br>
Band band = ds.GetRasterBand(1);<br>
ColorTable ct = band.GetRasterColorTable();<br>
ArrayList arraylist = new ArrayList();<br>
for (int i = 0; i < ct.GetCount(); i++)<br>
{<br>
ColorEntry ce = ct.GetColorEntry(i);<br>
Color cr1 = Color.FromArgb(ce.c4, ce.c1, ce.c2, ce.c3);<br>
arraylist.Add(cr1);<br>
}<br>
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</font></blockquote></div><br><br clear="all"><br>-- <br>Best regards,<br>Chaitanya kumar CH.<br>/tʃaɪθənjə/ /kʊmɑr/ <br>+91-9494447584<br>17.2416N 80.1426E<br>