A method for generating bitmap image data of a page includes acquiring print data of a page including compressed images, and performing rendering of bands included in the page based on the print data to generate the bitmap image data. The performing of the rendering performs rendering at least two of the bands concurrently. The performing of the rendering includes decompressing the compressed images, and using the decompressed images for corresponding bands of the bands to generate the bitmap image data. The decompressing decompresses, into a same memory area in a decompression buffer, at least two compressed images used for different bands, so that one of the two compressed images is decompressed into the same memory area and another of the two compressed images is decompressed, after rendering of a last band for which the one of the two compressed images is lastly used is finished, into the same memory area.

An image forming apparatus draws line by line an object included in a page. The image forming apparatus includes a sorting unit configured to sort edges of the object included on process target lines in ascending order of coordinates by comparing the coordinates of edges and a drawing unit configured to perform drawing between the edges based on the edges arranged by the sorting unit. The sorting unit compares coordinates to sort other edges on the process target lines with respect to the plurality of edges on the process target lines, which are already sorted, starting with a comparison with the coordinate of one of the plurality of edges specified based on the coordinates of the other edges.

An image processing device performs: breaking down a drawing command into horizontal line parameters each indicating a drawing parameter on a line-by-line basis; and reading, from a translucent image storage unit configured to store a translucent image including a translucency value indicating a transmission rate of a color value corresponding to pixel for each of a plurality of pixels, the translucency values of pixels corresponding to the horizontal line parameter, and writing color values designated by the horizontal line parameter directly into a color image storage unit configured to store a color image including a color value for each of a plurality of pixels as the color values of the respective pixels corresponding to the horizontal line parameter without reading the color values of the pixels corresponding to the horizontal line parameter from the color image storage unit, when all of the read translucency values indicate transparent.

An image forming apparatus draws line by line an object included in a page. The image forming apparatus includes a sorting unit configured to sort edges of the object included on process target lines in ascending order of coordinates by comparing the coordinates of edges and a drawing unit configured to perform drawing between the edges based on the edges arranged by the sorting unit. The sorting unit compares coordinates to sort other edges on the process target lines with respect to the plurality of edges on the process target lines, which are already sorted, starting with a comparison with the coordinate of one of the plurality of edges specified based on the coordinates of the other edges.

A method for generating bitmap image data of a page includes acquiring print data of a page including compressed images, and performing rendering of bands included in the page based on the print data to generate the bitmap image data. The performing of the rendering performs rendering at least two of the bands concurrently. The performing of the rendering includes decompressing the compressed images, and using the decompressed images for corresponding bands of the bands to generate the bitmap image data. The decompressing decompresses, into a same memory area in a decompression buffer, at least two compressed images used for different bands, so that one of the two compressed images is decompressed into the same memory area and another of the two compressed images is decompressed, after rendering of a last band for which the one of the two compressed images is lastly used is finished, into the same memory area.

An image processing device performs: breaking down a drawing command into horizontal line parameters each indicating a drawing parameter on a line-by-line basis; and reading, from a translucent image storage unit configured to store a translucent image including a translucency value indicating a transmission rate of a color value corresponding to pixel for each of a plurality of pixels, the translucency values of pixels corresponding to the horizontal line parameter, and writing color values designated by the horizontal line parameter directly into a color image storage unit configured to store a color image including a color value for each of a plurality of pixels as the color values of the respective pixels corresponding to the horizontal line parameter without reading the color values of the pixels corresponding to the horizontal line parameter from the color image storage unit, when all of the read translucency values indicate transparent.