Datasheet

PDF: 09005aef8202ec2e/Source: 09005aef8202ebf7 Micron Technology, Inc., reserves the right to change products or specifications without notice.
MT9D111__7_REV5.fm - Rev. B 2/06 EN
146 ©2004 Micron Technology, Inc. All rights reserved.
MT9D111 - 1/3.2-Inch 2-Megapixel SOC Digital Image Sensor
Firmware
Micron Confidential and Proprietary
To upload a custom gamma table, upload the values to the appropriate mode driver
locations (see Table 18, "Driver Variables-JPEG Driver (ID = 9)," on page 97), and select
the gamma table type to be three (user defined) for the particular mode. If a contrast
level is selected, it is applied to the user uploaded gamma table.
The driver contains settings for raw and output image size and pan for each mode. See
variables such as mode.sensor_col_width_A/B, mode.sensor_row_height_A/B and
mode.fifo_width_A/B, mode.fifo_height_A/B. Blanking and readout mode— the use of
skip, binning, and 1ADC modes— is configured using sensor core registers R5:1-8:1 and
R32:1, R33:1.
To change overall image brightness by changing adding luma offset at output, set
• mode.y_rgb_offset_A for preview
• mode.y_rgb_offset_B for capture
To change output for mat, set
• mode.output_format_A for preview
• mode.output_format_B for capture
Similarly, the user can set special effects for each mode using mode.spec_effects_A/B.
Histogram Driver
The histogram driver continually works to reduce image flare and continually analyzes
input image histogram and dynamically adjusts the black level, R59:1. When flare is
present the histogram does not contain dark tones, causing the driver to subtract off a
higher black level thus regaining the lost contrast. In certain situations the scene may
contain no dark tones without flare. The histogram driver cannot distinguish this situa-
tion and alters the black level just the same, causing the image to have more contrast,
which looks acceptable in many situations.
Variable hg.maxDLevel sets the maximum level that can be subtracted off the input data.
Set this value to match lens flare percentage. For example, if a lens typically has a
5 percent flare, set this value to 0.05*1024 = 51. To disable flare subtraction in all modes,
set this value to “0.” The maximum allowed value is 128. Read variable hg.DLevel to see
the current subtracted value. hg.percent indicates how many percent of histogram dark
tones need to be clipped. The recommended value is 0. The hg.DLevelBufferSpeed con-
trols the speed of adjustment, 32 being fastest and 1 being the slowest.
Flicker Avoidance Driver
Indoor light sources powered from the wall AC power supply often exhibit fast oscilla-
tions. The oscillations are too fast to be seen; their frequency often being the frequency
of the wall power supply. The oscillations interact with the sensor and can show in the
image as standing or rolling horizontal bars. Such bars are visible when sensor integra-
tion time is not a natural multiple of the flicker period. Since there are two AC frequen-
cies in common use, 50Hz and 60Hz, the imager integration time must match to
ambient indoor flicker frequency to produce good images.
The MT9D111 can automatically detect the presence of flicker and adjust its integration
time to avoid it.
To set up flicker avoidance program the following variables:
• fd.R9_step60 and fd.R9_step50 are flicker periods for 50 and 60Hz illumination
expressed in row time, fd.R9_step60=Tflk/Trow. For 60Hz (1/120)/Trow and for 50Hz
(1/100)/Trow. The light flicker frequency is twice the power frequency due to rectifica-
tion.