Image processing using processing by bands and fixed-size work buffer

A printer control apparatus comprising:

• a printer engine;
• a real-time decoding unit which decodes band coded data, converts data into video signals and transmits the video signals to the printer engine, without temporarily storing the decoded data in a band raster of memory;
• a non-real-time decoding unit which decodes the band coded data, stores the decoded data into a first area of the band raster area of the memory, converts data stored in a second area of the band raster area of the memory into video signals and transmits the video signals to the printer engine;
• a setting unit which sets a band height at a higher value if the real-time decoding unit is to be used, and sets a band height at a lower value if the non-real-time decoding unit is to be used;
• a rendering unit which renders bitmap data having the band height at the higher value into a band raster area of the memory when the band height is set to the higher value by the setting unit, and renders bitmap data having the band height at the lower value into a band raster area of the memory when the band height is set to the lower value by the setting unit;
• and
• an encoding unit which encodes the bitmap data rendered by the rendering unit into the band coded data,
• wherein the realtime decoding unit is activated after the bitmap data having the band height at the higher value is encoded by the encoding unit, and
• the non-real-time decoding unit is activated after the bitmap data having the band height at the lower value is encoded by the encoding unit.

A printer control method comprising:

• a real-time decoding step of using a realtime decoding unit to decode band coded data, convert data into video signals and transmitting the video signals to the printer engine, without temporarily storing the decoded data in a band raster of memory;
• a non-real-time decoding step of using a non-real-time decoding unit to decode the band coded data, storing the decoded data into a first area of the band raster area of the memory, converting data stored in a second area of the band raster area of the memory into video signals and transmitting the video signals to the printer engine;
• a setting step of setting a band height at a higher value if the real-time decoding unit is to be used, and setting a band height at a lower value if the non-real-time decoding unit is to be used,
• a rendering unit which renders bitmap data having the band height at the higher value into the band raster area of the memory when the band height is set to the higher value by the setting unit, and renders bitmap data having the band height at the lower value into the band raster area of the memory when the band height is set to the lower value by the setting unit;
• and
• an encoding unit which encodes the bitmap data rendered by the rendering unit into the band coded data,
• wherein the real-time decoding unit is activated after the bitmap data having the band height at the higher value is encoded by the encoding unit, and
• the non-real-time decoding unit is activated after the bitmap data having the band height at the lower value is encoded by the encoding unit.