Estimation of ink/toner coverage when printing
View Patent ↗In summary, the present invention provides a method, apparatus and program product for calculating an estimate of the amount of toner coverage required for printing print data defined in a compressed data stream. The estimate is obtained with reduced processing by obtaining coverage data from a partially decompressed formed of the data stream and using this to obtain the coverage estimate, thus removing the need to do a full de-compression of the data stream. For example the coverage data is a count of toned pixels for at least one intensity level.
1. A method of operating a printing system, comprising:
receiving a compressed Lempel-Ziv Welch (LZW) data stream comprising compressed LZW print data;
performing a partial decompression of the compressed LZW print data by at least partially creating a string table from the LZW data stream, the string table comprising a plurality of entries each with an associated string;
determining coverage data for the LZW print data using the partially decompressed print data by:
determining a toned pixel count for each string in the string table; and
using the determined toned pixel counts to determine a toned pixel count for the LZW print data;
estimating an amount of marking material to print the LZW print data using the determined coverage data; and
storing the estimated amount of marking material in a memory.
2. The method of claim 1 wherein the coverage data comprises a number of pixels for each of a plurality of intensity levels.
3. The method of claim 2 wherein:
the number of intensity levels in the plurality of intensity levels is based on a number of intensity levels indicated in the print data.
4. The method of claim 2 further comprising:
determining an intensity level for a pixel based on the intensity level of the pixel and at least one adjacent pixel.
5. The method of claim 1 wherein the coverage data is determined for a plurality of color planes.
6. The method of claim 1 further comprising:
using the estimate of an amount of marking material to determine a cost of printing the print data.
7. The method of claim 1 further comprising:
using the estimate of an amount of marking material to determine if a predetermined print device is capable of printing the print data.
8. A data processing system comprising:
at least one processor; and
an interface and memory accessible to the at least one processor;
wherein the interface receives a compressed Lempel-Ziv Welch (LZW) data stream comprising compressed LZW print data;
wherein the at least one processor is operable to perform sub-processes of:
partially decompressing the compressed LZW print data by at least partially creating a string table from the LZW data stream, the string table comprising a plurality of entries each with an associated string;
determining coverage data for the LZW print data using the partially decompressed print data by:
determining a toned pixel count for each string in the string table; and
using the determined toned pixel counts to determine a toned pixel count for the LZW print data; and
estimating an amount of marking material to print the LZW print data using the determined coverage data; and
storing the estimated amount of marking material in the memory.
9. The data processing system of claim 8 wherein the coverage data comprises a number of pixels for each of a plurality of intensity levels.
10. The data processing system of claim 9 wherein:
the number of intensity levels in the plurality of intensity levels is based on a number of intensity levels indicated in the print data.
11. The data processing system of claim 9 wherein the at least one processor is further operable to perform a sub-process of:
determining an intensity level for a pixel based on the intensity level of the pixel and at least one adjacent pixel.
12. The data processing system of claim 8 wherein coverage data is determined for a plurality of color planes.
13. The data processing system of claim 8 wherein the at least one processor is further operable to perform a sub-process of:
using the estimate of an amount of marking material to determine a cost of printing the data stream.
14. The data processing system of claim 8 wherein the at least one processor is further operable to perform a sub-process of:
using the estimate of an amount of marking material to determine if a predetermined print device is capable of printing the data stream.
15. A computer program product comprising a non-transitory program storage medium readable by a computer, the medium embodying one or more programs of instructions executable by a computer to perform a method comprising:
receiving a compressed Lempel-Ziv Welch (LZW) data stream comprising compressed LZW print data;
performing a partial decompression of the compressed LZW print data by at least partially creating a string table from the LZW data stream, the string table comprising a plurality of entries each with an associated string;
determining coverage data for the LZW print data using the partially decompressed print data by:
determining a toned pixel count for each string in the string table; and
using the determined toned pixel counts to determine a toned pixel count for the LZW print data;
estimating an amount of marking material to print the LZW print data using the determined coverage data; and
storing the estimated amount of marking material in a memory.
16. The computer program product of claim 15 wherein coverage data comprises a number of pixels for each of a plurality of intensity levels.
17. The computer program product of claim 16 , the method further comprising:
determining an intensity level for a pixel based on the intensity level of the pixel and at least one adjacent pixel.
18. The computer program product of claim 15 wherein the coverage data is determined for a plurality of color planes.
19. The computer program product of claim 15 , the method further comprising:
using the estimate of an amount of marking material to determine a cost of printing the print data.
20. The computer program product of claim 15 , the method further comprising:
using the estimate of an amount of marking material to determine if a predetermined print device is capable of printing the print data.