Processing images

An Adaptive Image Resolution Enhancement Technology (IRET) process and apparatus are described to improve halftone imaging by changing ordered halftone screen resolution according to the content of the image and managing these changes based on image content. The Adaptive IRET halftoning technique maximizes the artifact reducing properties of coarser ordered screens, while minimizing the loss of rendered detail in image areas having highly spatial frequency. IRET may utilize a mixture of any ordered halftone screen (e.g. clustered-dot dither, line screen, etc.) to generate halftone dots with a number of levels, and any dispersed halftone screen to generate additional levels for the ordered halftone dots. Adaptive IRET uses an activity index to change its ordered halftone screen resolution according to the content of the image. To render a page with a mixture of text, line art, area fill, and photograph, the "busy" areas, such as text, line art, and edge regions in a photograph, are rendered with a higher resolution screen. Smooth areas, such as area fill and non-edge regions in a photograph, are better rendered with a lower resolution screen.