1. An image forming apparatus for forming a color image using color materials of a plurality of colors that include a basic color, black and at least one special color, comprising:
an input unit for inputting color image data for which an image is to be formed;
a color separation unit for generating color data in which the color image data has been separated into each of the plurality of colors; and
an image forming unit for forming a color image based upon the color data;
wherein said color separation unit generates the color data so that the color data has a region in which amount of the color material of the color black used is increased and amount of the color material of the special color used is increased as brightness declines in a low-brightness region in the hue of the special color.
2. The apparatus according to claim 1, wherein said color separation unit sets, as a high-brightness region, a brightness region from maximum brightness to a brightness corresponding to a maximum saturation that the color material of the special color is capable of reproducing; and
in the high-brightness region, generates color data in such a manner that the amount of color material of the special color used increases as brightness declines.
3. The apparatus according to claim 1, wherein said color separation unit sets, as an intermediate-brightness region, a brightness region from a lower-limit brightness of a high-brightness region to a brightness at which maximum saturation is obtained by a mixed color of the two basic colors;
in the intermediate-brightness region, generates color data in such a manner that the amounts of color materials of the two basic colors used increase as brightness declines with amount of color material of the special color used being maximized until a limit on total amount of the color materials used is reached; and
generates color data in such a manner that the amount of color material of the special color used decreases and amounts of color materials of the two basic colors used increase as brightness declines, after the amount of color materials used reaches the limit on total amount used.
4. The apparatus according to claim 1, wherein said color separation unit sets, as a low-brightness region, a brightness region from a lower-limit brightness of an intermediate-brightness region to a brightness at which maximum saturation is obtained by a mixed color of the special color and black; and
in the low-brightness region, generates color data in such a manner that the amounts of color materials of the two basic colors used decrease and amounts of the materials of the special color and black used increase as brightness declines.
5. The apparatus according to claim 1, wherein said color separation unit sets a brightness region from a lower-limit brightness of a low-brightness region to minimum brightness as a near-black region; and
in the near-black region, generates color data in such a manner that amount of color material of the special color used decreases and amount of material of the black color used increases as brightness declines.
6. The apparatus according to claim 1, wherein the color material of the special color expresses a brightness higher than that of a secondary color in a hue near the hue of the special color expressed by a mixed color of two of the basic colors.
7. The apparatus according to claim 1, wherein the color material of the special color has an unwanted absorption component of spectral reflectance that is smaller than that of two color materials, which have hues near the special color, from among the basic colors.
8. The apparatus according to claim 1, wherein in a case where a first mixed color obtained by mixing the color material of the special color and the material of the black color is adjusted to a hue and brightness that are the same as those of a second mixed color obtained by mixing two color materials, which have hues near the special color, from among the basic colors and the color material of the color black, an image based upon the first mixed color has an unwanted absorption component of spectral reflectance that is small in comparison with an image based upon the second mixed color.
9. The apparatus according to claim 1, wherein the special color is any color from among red, green and blue.
10. The apparatus according to claim 9, wherein the basic colors include cyan, magenta and yellow.
11. The apparatus according to claim 1, wherein said color separation unit uses a color material of a complementary color with respect to the special color instead of the material of the black color in a low-brightness region of the hue of the special color.
12. A method of controlling an image forming apparatus for forming a color image using color materials of a plurality of colors that include a basic color, black and at least one special color, said method comprising:
an input step of an input unit inputting color image data for which an image is to be formed;
a color separating step of a color separation unit generating color data in which the color image data has been separated into each of the plurality of colors; and
an image forming unit of an image forming unit forming a color image based upon the color data;
wherein the color data is generated at said color separation step so that the color data has a region in which amount of the color material of the color black used is increased and amount of the color material of the special color used is increased as brightness declines in a low-brightness region of the hue of the special color.
13. A computer-readable storage medium storing a computer program for implementing the image forming apparatus set forth in claim 1 by being run on a computer within the image forming apparatus.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
What is claimed is:
1. A method for measuring an output multiplixer (OMUX) transfer function, comprising:
receiving a broadcast downlink signal from a satellite;
demodulating the broadcast downlink signal;
remodulating the demodulated signal; and
comparing the received broadcast downlink signal to the remodulated signal to estimate the OMUX transfer function of the satellite.
2. The method of claim 1, wherein the steps are performed by a receiver.
3. The method of claim 1, wherein input multiplexor effects are negligible.
4. The method of claim 1, wherein the remodulating includes accounting for traveling wave tube amplifier (TWTA) maps.
5. The method of claim 1, wherein the estimated OMUX transfer function comprises a ratio of the received broadcast downlink signal to the remodulated signal.
6. The method of claim 1, wherein the received broadcast downlink signal comprises an estimated OMUX output due to noise.
7. The method of claim 1, wherein the estimated OMUX transfer function includes bandwidth, flatness, and group delay.
8. The method of claim 1, further comprising utilizing the estimated OMUX transfer function to assist to layered modulation signal processing.
9. The method of claim 1, further comprising utilizing the estimated OMUX transfer function as part of satellite payload system monitoring.
10. An apparatus for measuring an output multiplixer (OMUX) transfer function, comprising:
means for receiving a broadcast downlink signal from a satellite;
means for demodulating the broadcast downlink signal;
means for remodulating the demodulated signal; and
means for comparing the received broadcast downlink signal to the remodulated signal to estimate the OMUX transfer function of the satellite.
11. The apparatus of claim 10, wherein the apparatus comprises a receiver.
12. The apparatus of claim 10, wherein input multiplexor effects are negligible.
13. The apparatus of claim 10, wherein the means for remodulating includes means for accounting for traveling wave tube amplifier (TWTA) maps.
14. The apparatus of claim 10, wherein the estimated OMUX transfer function comprises a ratio of the received broadcast downlink signal to the remodulated signal.
15. The apparatus of claim 10, wherein the received broadcast downlink signal comprises an estimated OMUX output due to noise.
16. The apparatus of claim 10, wherein the estimated OMUX transfer function includes bandwidth, flatness, and group delay.
17. The apparatus of claim 10, further comprising means for utilizing the estimated OMUX transfer function to assist to layered modulation signal processing.
18. The apparatus of claim 10, further comprising means for utilizing the estimated OMUX transfer function as part of satellite payload system monitoring.
19. A system for measuring an output multiplixer (OMUX) transfer function, comprising:
a downlink signal broadcast from a satellite;
a receiver configured to receive the downlink signal;
a demodulator within the receiver configured to demodulate the downlink signal;
a remodulator within the receiver configured to remodulate the demodulated signal; and
a comparator configured to compare the received downlink signal to the remodulated signal to estimate the OMUX transfer function of the satellite.
20. The system of claim 19, wherein input multiplexor effects are negligible.
21. The system of claim 19, wherein the remodulator accounts for traveling wave tube amplifier (TWTA) maps.
22. The system of claim 19, wherein the estimated OMUX transfer function comprises a ratio of the received broadcast downlink signal to the remodulated signal.
23. The system of claim 19, wherein the downlink signal received by the receiver comprises an estimated OMUX output due to noise.
24. The system of claim 19, wherein the estimated OMUX transfer function includes bandwidth, flatness, and group delay.
25. The system of claim 19, further comprising a layered modulation module configured to utilize the estimated OMUX transfer function to assist to layered modulation signal processing.
26. The system of claim 19, further comprising a system monitoring module configured to utilize the estimated OMUX transfer function as part of satellite payload system monitoring.