1. Field of the Invention
This invention relates to raster image processors (RIP), and in particular, it relates to a raster image processor operating in a banding mode.
2. Description of Related Art
Raster image processors (RIPs) are processors that generate bitmap images from print language such as a PDL (Page Description Language). An example of a RIP is Adobe®'s Configurable Postscript Interpreter (CPSI), which generates raster imaged from PostScript® data. RIPs commonly use two modes to produce images, namely, a full-frame mode and a banding mode. In the full-frame mode, the RIP produces the image in one large block. In the banding mode, the RIP produces the image in smaller blocks referred to as bands. The RIPs typically allows the size of the bands produced to be configurable. In a conventional RIP, a constant band size is typically used for each print job.
It has been found that the best data throughput is achieved when the band size is set to a value proportional to the size of the L2 cache on the CPU. In particular, the best performance is achieved when the band size is set to a value that allows one band to fit within the L2 cache. In addition to the size of the L2 cache, other significant factors affecting throughput of the RIP include application load and application behavior. With varying system conditions, it cannot be guaranteed that a fixed band size will result in a constant level of performance.
Accordingly, the present invention is directed to a raster image processor and related methods that substantially obviate one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to maximize the throughput of the RIP.
Additional features and advantages of the invention will be set forth in the descriptions that follow and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims thereof as well as the appended drawings.
To achieve these and/or other objects, as embodied and broadly described, the present invention provides a method implemented in a raster image processor for producing images using a banding mode, which includes: (a) setting an initial value for a band size used to produce an image; (b) automatically and continuously adjusting the band size; and (c) generating one or more images using the adjusted band size.
In another aspect, the present invention provides a computer program product that causes a data processing apparatus to perform the above method.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
Embodiments of the present invention provide a method by which a raster image processor operating a banding mode automatically reconfigures its memory usage to achieve optimum throughput, i.e., to maximize the amount of data produced per unit time. To accomplish this, the RIP monitors its memory usage and its throughput and reconfigures its memory usage accordingly.
In a preferred embodiment of the present invention, in order to avoid an excessive amount of changes, the band size adjustment will only occur after some interval of pages has been processed or some amount of time has elapsed since the last adjustment. Accordingly, as shown in
If band size adjustment is desired (“N” in step S2), the RIP determines whether or not the current throughput at the current band size value is lower than a previous throughput (step S3). If performance has worsened with the current band size compared to a previous band size value (“Y” in step S3), then the band size is reverted to a previous value corresponding to the best previous throughput (step S5). If performance has increased as compared to past values (“N” in step S3), then the band size is recomputed (step S4). In the recomputing step, the band size is changed in the same direction as the last change. For example, if the last change was a decrease in band size, since performance was positively affected, the current change will also be a decrease. In a preferred embodiment, the band size is changed in step S4 by a fixed amount such as 8k, 64k, etc. Alternatively, the band size may be changed by an amount that various with the amount of improvement in performance. In both steps S4 and S5, the RIP is reconfigured using the changed band size value. Raster image processing is then performed on the page (step S6). The portion of the RIP that performs raster image processing, i.e., generating the bitmap image, can be implemented by an existing RIP. This process (steps S1 to S6) is repeated until all pages in the PDL are processed.
As can be seen from the above description, embodiments of the present invention provides an RIP operating in a self-tuning banding mode in that during the raster image processing, the RIP continuously (including periodically and intermittently) and automatically adjusts the size of the band used to produce the image.
In the method described above, the band size adjustment is performed at the start of a page (either every page, or periodically after certain number of pages or amount of time since the last adjustment). This is convenient because many existing RIPs allow for band size adjustment at the start of a page, but the invention is not limited to such timing. More generally, the invention can be applied such that band size is adjusted at the start of a new unit of image, where a unit may be a page, multiple pages, a portion of a page, or any other suitable unit of image.
The methods described above may be implemented as a part of a raster image processor, which may be a part of a printer, a client computer, a print server, or any other suitable data processing system. It may be used to generate a raster image which may be utilized in any desired ways, such as to be printed on a printer, to be display on a display device, to be stored in a storage device, to be transferred to another device, etc.
It will be apparent to those skilled in the art that various modification and variations can be made in the raster image processor of the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover modifications and variations that come within the scope of the appended claims and their equivalents.
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