How to create layers like Photoshop

How can I create a transparent layer over an image or create a duplicate layer of the image for editing without changing the original layer?

You can create an annotation stamp object over the original image and assign a copy of the original image to the annotation stamp object.
The annotation stamp object gives you the ability to specify a transparent color (for example, if the background of the image is white, you can set white as transparent color).
The details depend on the programming interface (C DLL, .Net classes, etc.) that you use. For example, if you are using LEADTOOLS .Net classes, you can use the AnnStampObject class. For more information, please see the following page:
http://www.leadtools.com/help/leadtools/v175/dh/an/leadtools.annotations~leadtools.annotations.annstampobject.html

Also, PSD files support layers and you can add the layers to a RasterImage object and then save them using the RasterCodecs.SavePsdWithLayers() Method. Note that you can specify layers information by using the CodecsPsdLayerInfo class. There are different options for each layer, including features for opacity and transparency.
For details, see http://www.leadtools.com...sdlayerinfo_members.html

Note: These links are valid at time of posting this reply.

Thanks,
Maen Badwan
LEADTOOLS Technical Support