To overcome commonly-used filtering template's drawback and remove the ringing artifact& block effect in conventional image filtering

this paper presents 2D all-phase window filtering under arbitrary orthogonal transform.Based on the general calculating formula of 2D all-phase template under arbitrary orthogonal transform

the concise formula of all-phase template with window under DFT is deduced.The restoration experiment on the sub-sampled image proves that: compared with the template constructed by IDFT

the PSNR of the image restored by all kinds of all-phase template is above 7dB higher and ringing artifact can be eliminated.Another experiment shows that block effect in conventional block filtering can be completely removed by employing 2D all-phase DCT template.