http://nssdc.gsfc.nasa.gov/photo_gallery/photogallery-mars.html#hst

Controversial Features

The following images were taken by the Viking 1 and 2 orbiters. They are 
among the most requested images which NSSDC archives. These images were 
taken of the region on Mars known as Cydonia Mensae and contain the feature 
commonly known as the "face". All of the images here have been rotated 
clockwise 90 degrees to reorient them so that north is toward the upper 
left corner. There are two versions of the images present here. The first 
of each pair is an unprocessed ("raw") version of the image taken of the 
area. Other than the processing necessary to create a JPEG image from the 
PDS formatted image file, the images are unchanged from the originals on 
Volumes 10, 11, 21, 28, and 63 of the Mission to Mars: Viking Orbiter 
Images of Mars CD-ROM set. The second of each pair has had the noise 
level reduced and the image sharpened using Image4PDS, a freeware program
 available from NSSDC. Finally, Color It!(tm) was used to adjust the 
contrast. (If you have any questions about the "face" on Mars, please 
refer to our Planetary Frequently Asked Questions page. Detailed 
information on the first two exposures (035A72 and 070A13) is also 
available.) The sizes of these images range from 120-504 KB. The raw 
images are also available in TIFF format on the Photo Gallery FTP site 
at ftp://nssdc.gsfc.nasa.gov/pub/photo_gallery/hi-res/planetary/mars/. 

FACE1.JPG (035A72)
FACE2.JPG (070A13)

"Face on Mars" images (40.9N, 9.45W) - Viking Orbiter 1
___________________________________________________________
Image:                             35A72          70A13
------                             -----          -----
Image number                     26588045       27280098
Orbit                               35             70
Central latitude                  40.89          40.64
Central longitude                  9.66           9.27
Image date (UT)                 1976-07-25     1976-08-30
Image time (UT)                  15:25:14       12:38:33
Local time                        18.56          16.84
Earth received date (UT)        1976-07-26     1976-08-30
Earth received time (UT)         21:11:28       17:09:45
CD_ROM Volume                    VO_1010        VO_1011
Sun azimuth (deg)                294.28         277.04
Sun zenith angle (deg)            79.93          62.59
Phase angle (deg)                 86.26          71.77
Spacecraft azimuth (deg)         169.05         139.54 
Spacecraft zenith angle (deg)     10.58          12.42 
Ground resolution (m/pixel)       51.73          48.13
Scaled pixel width (km)            0.047          0.043
Scaled image height (km)          49.6           46.0
Scaled image width (km)           56.8           52.3
Spacecraft range (km)             1873           1725
Spacecraft altitude (km)          1853           1698
Subspacecraft azimuth (deg)      322.57         311.09
Subspacecraft latitude (deg)      37.04          37.14
Subspacecraft longitude (deg)      8.65           6.00
Subsolar azimuth (deg)            89.61          88.04
Subsolar latitude (deg)           24.84          22.58
Subsolar longitude (deg)         108.00          81.83
Solar longitude (deg)             99.29         115.60
Incidence angle (deg)             80.01          62.65
Emission angle (deg)              10.24          12.13
North azimuth (deg)              155.35         170.70
True anomaly angle (deg)          31.79          24.44
Visual imaging camera               B              A
Filter                            clear          clear
Exposure duration (sec)          0.033940       0.016970
___________________________________________________________
Both images were taken during Martian northern summer in the afternoon.