I need to transform RGB map to IHS is that feature available in QGIS?
The tool to complete this in QGIS is part of a plugin called GRASS.
Some resources for learning about this tool and GRASS:
The tool takes three input images (corresponding to red, green, and blue) and outputs three images (corresponding to intensity, hue, and saturation). If your input image is single RGB colour-composite just use the
SplitColourComposite tool to create the three inputs.