Since 2D CAD engineering graphics require high precision

a wavelet domain based reversible watermarking algorithm for 2-Dimensional CAD engineering graphics by using improved quantization index modulation (IQIM) is proposed in this paper. First

all vertices in the 2D CAD engineering graphics are extracted

and then Log-polar Mapping and discrete wavelet transform are done to them respectively to achieve the invariance of affine transform. Finally

the encrypted watermark is embedded into detailed coefficients by using improved quantization index modulation (IQIM) scheme. Experimental result shows that the proposed algorithm has a large capacity

good invisibility

and robust against the attacks such as transformation

rotation

equal scaling etc.