Hello Chaitra,
the Alpha8 image format is a one byte per pixel format and each pixel is used as an alpha value: 0x00 means full transparent and 0xFF means full opaque (full colored).
I think the problem in your EwLoadExternBitmap() implementation is the color conversion from your source color format into this Alpha8 format. Correct?
Do you have a source image that contains an alpha channel (e.g. some RGBA format) or do you have an image without alpha channel and you want to convert that into some gray values that should be used as alpha values?
Can you share an example of what you have and what you want to get? Then it should be possible to find a solution....
Best regards,
Manfred.