Georeferencing-error

[av]

I have a image which I need to georeference and use it as a background image in hec ras. I used Arcmap 10.1 and georeferencing tool for this purpose. After rectifying when i want to save the image as Jpg or Gif or bitmap this following error comes up
output file format with specified pixel type or number of bans or color map is not supported
How can I fix it?
Thanks in advance

[NidhinKarthikeyan]

There are some raster formats that can only support a subset of data types, number of bands, or a colormap. If you specify some features that are not supported by the format, this warning occurs. You can use TIFF, IMAGINE Image, etc..

Take a look at Supported raster dataset file formats.

[av]

Thanks nidhinkn for your response.
I tried to save the image as Tiff but it turned to a black image. Is there any reason for this? 
cheers.

[NidhinKarthikeyan]

Try to 'Calculate Statistics'(Right click on the image and select Calculate Statistics) on the Tiff image. Also delete the pyramid and rebuild the pyramid. If it doesn't help, try to export it into Imagine Image format or Grid format.