Viking Orbiter 1 mosaic of the region from Argyre Planitia to Thaumasia Fossae. Mosaic is made from 36 filtered (violet, red filter) images. East is up and north is to the left.
Viking 1 obtained the 36 frames for this mosaic (numbers 034A11 to 034A46) through two filters (purple and red). A green-filter image was synthesized from these two. The exact resolution of the mosaic is not stated (the Viking image archive contains only very vague information on image resolution), but based on the sizes of named craters, the full-size enlargement has a resolution of about 800 meters per pixel. While making the mosaic the images were warped and slightly enlarged, so the smallest visible details are probably about 2 kilometers in diameter. To learn more about this image, visit Daniel Machacek's blog (in Czech, but Google Translate makes it quite readable).