Status changed to 'Confirmed' because the bug affects multiple users.
** Changed in: hplip (Ubuntu)
Status: New => Confirmed
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https://bugs.launchpad.net/bugs/1036236
Title:
hpcups and hpijs driver use different rasterization
Status in HP Linux Imaging and Printing:
Confirmed
Status in “hplip” package in Ubuntu:
Confirmed
Bug description:
HPLIP provides two drivers for the Laserjet 1515n: hpcups and hpijs:
- hp-color_laserjet_cp1515n-hpijs-pcl3.ppd
- hp-color_laserjet_cp1515n-pcl3.ppd
The new hpcups shall replace the old hpijs, however, it produces very
different rasterization results, resulting in a radically different
visual impression. Differences are especially prominent for greyscale
prints.
Hpcups produces "amplitude modulation" halftones (dots of different
sizes at fixed locations). When resolution is set to "Normal", the
size of these dots is so large that contours cannot be reproduced with
reasonable detail. Heavy aliasing can be easily seen in the circle
contours on the Ubuntu Printer test page. Printing photographs in
greyscale mode yields badly rasterized images like those known from
low-quality newspaper prints (dot pattern is so prominent it dominates
image contours). Artifacts are reduced, but still visible at
resolution "Best".
In contrast, hpijs produces "frequency modulation" halftones with
stochastic dithering (small-sized dots placed at varying densities).
At resolution "Normal", it produces evenly colored areas with
reasonably sharp edges. Circle contours on the Ubuntu Printer test
page appear continuous. Photographs are reproduced at a a much higher
fidelity as with the hpcups driver.
Questions:
1. Why do the two drivers use different rasterization?
2. Why is the result of rasterization so bad in the hpcups driver, set at
resolution "Normal, Greyscale"?
Note:
Both drivers produce acceptable color prints with much viewer artifacts
visible, even at resolution "Normal".
ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: hplip 3.12.2-1ubuntu3.1
ProcVersionSignature: Ubuntu 3.2.0-29.46-generic 3.2.24
Uname: Linux 3.2.0-29-generic i686
ApportVersion: 2.0.1-0ubuntu12
Architecture: i386
CurrentDmesg: [ 63.368304] init: plymouth-stop pre-start process (1700)
terminated with status 1
Date: Mon Aug 13 16:38:16 2012
Lpstat: device for Farblaser: hp:/net/HP_Color_LaserJet_CP1515n?zc=NPIE56824
MachineType: exone D156200
Papersize: letter
PpdFiles: Farblaser: HP Color LaserJet cp1515n pcl3, hpcups 3.12.2
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.2.0-29-generic
root=/dev/mapper/lvmvg-Root ro quiet splash vt.handoff=7
SourcePackage: hplip
UpgradeStatus: Upgraded to precise on 2012-04-26 (108 days ago)
dmi.bios.date: 04/23/2004
dmi.bios.vendor: FUJITSU SIEMENS // Phoenix Technologies Ltd.
dmi.bios.version: 4.06 Rev. 1.09.1562
dmi.board.name: D1562
dmi.board.vendor: FUJITSU SIEMENS
dmi.board.version: S26361-D1562
dmi.chassis.type: 6
dmi.chassis.vendor: exone
dmi.modalias:
dmi:bvnFUJITSUSIEMENS//PhoenixTechnologiesLtd.:bvr4.06Rev.1.09.1562:bd04/23/2004:svnexone:pnD156200:pvr:rvnFUJITSUSIEMENS:rnD1562:rvrS26361-D1562:cvnexone:ct6:cvr:
dmi.product.name: D156200
dmi.sys.vendor: exone
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