Automatic detection of black and white pages in a color document stream
AssigneeXerox Corporation
InventorsMarc Raymond Grosso, Craig D. Woodward
Life of this patent
Estimating the term…
Abstract
An approach is provided for identifying black and white pages in a color document stream. This approach may be utilized in digital printing systems. This approach examines a small portion of the color data for a page to identify whether the color data is indicative of the page being a black and white page or a full color page. This approach also examines the relative sizes of compressed color separations for the pages. Pages that are determined to be black and white pages may be printed in a black and white mode, whereas full color pages may be printed in a full color page mode.
Claims7
A method for processing a selected page of a mixed document having at least one full color page and at least one black and white page, the selected page containing at least one of compressed color separation layers of cyan, magenta, yellow and black, comprising the steps of:
- comparing the respective sizes of the compressed color separation layers to determine if the sizes are equal;
- where the sizes of the compressed color separation layers are not equal, printing the selected page as a color page, otherwise comparing the size of the compressed black separation layer to one of the other compressed color separation layers;
- and
- where the compressed black separation layer is larger, printing the selected page as a black and white page.
A method for processing a selected page in a mixed document from a print source having a plurality of pages, comprising the steps of:
- (a) sending the mixed document from the print source to a digital front end having a decomposer, an internal frame store, a resource manager, and an electronic precollation subsystem;
- (b) decomposing the selected page into four color separation layers holding color data, the color separation layers being cyan, magenta, yellow and black;
- (c) forwarding the color separation layer data to the internal frame store where the data is buffered;
- (d) analyzing the color separation layer data received in the internal frame store to determine whether the selected page is a black and white page;
- (e) where the selected page is determined to be a black and white page, analyzing a portion of a given color separation layer to determine whether all of the color separation layer data for the portion has the same value and then forwarding the color separation layer data to the resource manager;
- (f) where the selected page is determined to be not a black and white page, forwarding the color separation layer data to the resource manager for further processing;
- (g) compressing the color separation layers and reporting the size of the compressed color separation layers to the internal frame store;
- (h) comparing the sizes of the compressed cyan color separation layer, the compressed magenta color separation layer, and the compressed yellow color separation layer to determine if the sizes of the compressed separation layers are equal;
- (i) where the sizes of the compressed separation layers are not equal, printing the selected page as a color page;
- (j) where the sizes of the compressed separation layers are equal, comparing the size of the compressed black color separation layer to one of the other compressed color separations layers;
- (k) where the compressed black color separation layer is larger, printing the selected page as a black and white page;
- (l) where the compressed black color separation is smaller, printing the selected page as a color page.
Dependencies are inferred from the claim text.