HP Designjet T1100ps A0 User Manual

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1.b Most of the colors are OK but certain ones are very different 
 
Follow the steps 1 to 5 as in 1.a and proceed from there:  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2.4.2.2 Grays are wrong in a color copied image 
 
Follow steps 1 to 4 as in 1.a There is an overall color cast in section 2.4.2.1.  If the 
problem persists, try cleaning the white background plate that is on the top assembly of 
the scanner over the glass plate. Alternatively use the Black ink only setting in the 
Print settings dialog box, if your printer has this setting. 
 
Note: the Black ink only setting is not available with some printers. 
 
 
2.4.2.3 The copy is not as shiny as the original 
 
This may be due to not using the correct media: High Gloss or Semi Gloss media should 
be used in this case. 
 
 
2.4.2.4 There is a big difference between right and left sides of the copy 
 
This may be due to the some miscalibration of the cameras. Try performing scanner 
maintenance. If this does not solve the problem, please contact the HP Support 
Organization.  
 
 
2.4.2.5 The background results colored when copying newspapers 
 
Are some of the colors 
non-reproducible?  
See section 3.2 in the 
Annex
System Limitation. Try 
modifying saturation 
and/or lightness 
Contact HP Support Organization
Yes
No
 
						

							22/52   Color Reproduction for the HP Large Format Color Copier products family.  To avoid copying the background of a background-colored document (typically sepia) 
you should use the background cleaning option when scanning in color mode; if you 
are interested in B&W copying you should use either Sepia or Blueprint type of original.   
 
2.4.2.6  Vertical bands appear in the copy 
 
This normally happens when the glass plate is dirty (either because it was dirty before 
the scanning or because the original left tiny bits of coating as it moved over it). In the 
first case, clean the glass plate according to the scanner maintenance procedure, and 
calibrate the scanner; in the second case, laminate the original (if possible) or place a 
transparent cover over it before scanning again. 
 
2.4.2.7 A B&W image appears greenish (or pinkish, or bluish) 
 
If you selected scanning in B&W and the output image has a noticeable color cast, then 
probably the problem is in the printer itself. Some products of the HP Large Format 
Color Copier family have an option to print using “Black ink only”, instead of a 
composite black made up of other colors available in your printer; this is a possible 
solution. If not available, make sure that the printer CLC (Closed-Loop Color) has been 
performed and is active. See section 3.1.4 for details on the CLC process. If this does 
not solve the problem, consider copying in Color mode. If the problem persists, follow 
the steps described in section 2.4.2.2. 
 
						

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3. ANNEX 
 
3.1 Color reproduction: theory of operation 
 
The following is a theoretical treatment of the technology involved in the 
scanning and reproduction of images. The technology at work in your particular 
product may be slightly different from that referred to the description that 
follows. 
 
Color reproduction consists of transferring an original image that resides on a substrate 
onto another substrate (paper or other media), as accurately as possible. With HP Color 
Copier systems reproduction is done by digitizing the original image with a large 
format scanner, applying color transformations and image enhancements, and finally 
sending the data to a large format printer to generate the reproduction of the image. 
 
There are five components involved in this process as depicted by the following picture: 
 
1) The original image 
2) The image digitizer (large format scanner) 
3) The color transformation and image enhancement engine (touch screen) 
4) The image producer (large format printer) 
5) The reproduced or final image 
 
 
 
						

							24/52   Color Reproduction for the HP Large Format Color Copier products family.  The principle behind color reproduction is that the original and the final image relate to 
each other according to the desired reproduction intent. 
 
It is also important to underline that the process includes image enhancement. This 
feature is included so that when the original is noisy, badly contrasted or imperfect, the 
resulting output can be enhanced (smoother, better contrasted, with enhanced edges 
and lines). In this case, the process is mainly driven by image enhancement rather than 
color reproduction fidelity. 
 
The following sections describe in more detail each component of a HP Color 
Reproduction system. 
 
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The original is where the image to be reproduced resides. In relation to color and 
image enhancement, originals can be classified as follows: 
 
• According to the way the image was created:
 
o Inkjet originals 
# Thermal Inkjet 
# Piezoelectric Inkjet 
# Continuous Inkjet 
o Non-Inkjet originals 
# Press/Offset 
# Silver Halide (traditional photography) 
# Electro photography: 
- Dry ink (toner): laser printers 
- Liquid ink: Digital Press  
# Others 
 
• According to the contents of the image:
 
o Pictorial images 
o Maps and graphic images with solid areas 
o CAD and drawings with solid lines 
o Text Documents 
 
• According to the color content:
 
o Color images 
o Monochromatic images: 
# Black and white 
# Sepia 
# Blueprint 
 
 
 
						

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• According to the shadows or contrast levels: 
o two levels: only black and white (e.g. text document) 
o multilevel: many gray levels (e.g. picture) 
 
• According to the original’s conditions:
 
o Clean image 
o Damaged or noisy original: 
# Stained, marked, smudged, spotted, … 
# Scratched, torn, … 
 
It is important to know what type of original you are handling in order to use the correct 
reproduction settings.  
 
When using a color reproduction system it is also very important to handle the original 
with maximum care in order not to damage it and to be able to generate a good copy.  
 
Finally, it is very important to make sure that, if the original has been recently printed, it 
is completely dry before using it. 
 
 
						

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The scanner is the device that digitizes the original and sends it to the processor for 
further digital treatment. It consists of a light source, a paper movement mechanism, 
RGB image sensors (two or more cameras) and the electronics required to process the 
data from the sensors. 
 
 
 
 
 
 
 
						

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3.1.2.1 Light source 
 
The light source provides enough light along the vision strip so that, after being 
modified by the original image
2, there is sufficient reflected light to reach the image 
sensors. 
  
The light source (lamp) stabilizes after the scanner has been on for approximately one 
hour. Therefore, if the color reproduction is critical and you don’t want to see 
differences from one end of the copy to the other, it is advisable to start scanning one 
hour after powering on the scanner. 
 
 
3.1.2.2 Paper movement and glass plate 
 
Since only one strip of the original image at a time is “seen” by the color sensors, either 
the sensors are moved to scan the original (as in most home/office scanners) or, as in 
the case of a large format scanner, the original is moved through a looking glass by a 
roller mechanism. 
 
As the paper is moved over, small fragments of the original media or dust stuck onto the 
glass plate may cause image quality problems, like undesired vertical streaks appearing 
on the copy. To minimize this problem make sure that your original is completely dry 
before loading it into the scanner and, as previously mentioned, handle it with care, 
choosing the proper document height in the loading mechanism. If the original is thicker 
than 2 mm, refer to guidelines for scanning thick media. Take care to protect the 
scanner from dust. 
 
 
3.1.2.3 Cameras 
 
There are three cameras to digitize the full width of the original image. Each of them 
consists of an optics part
3 and a CCD (Charge-Coupled Device), which are similar to 
the active elements found in digital cameras. The CCD is able to digitize the color of the 
pixels into four components: Black, Red, Green and Blue. When scanning in Black and 
White mode a combined signal is produced from the Red, Green and Blue signals 
(some CCDs can generate it directly). 
 
                                       
 2 Red patches absorb more light in the blue, green and yellow parts of the visible spectrum than in the red 
part. 
3 The optics part of a camera is a series of mirrors and lenses that enable the small CCD to see a wider 
part of the original. 
 
						

							28/52   Color Reproduction for the HP Large Format Color Copier products family. 
 
The cameras must be periodically calibrated in order to avoid undesired geometrical 
distortions in the final copy, as well as ensure a correct color capture. Calibration can 
be performed using the scanner maintenance tool provided with the system. It is 
advisable to run the scanner calibration every time the system warns the user to do so, 
or when any of the following defects appear: jagged lines, blurry images, modified 
colors (with respect to previous copies). 
 
3.1.2.4  Electronics 
 
After each strip has been digitized, the electronics compose the whole image and apply 
several image treatments and linearizations to correct geometrical and color space 
distortions. The result is a digital image ready to be sent to the touch screen, which in 
turn will either store the image or send it to the printer. 
 
During the scanner maintenance process, the electronics calibrate all the responses from 
other elements (light, optics and CCDs) and between the CCDs themselves to obtain an 
accurate response. 
 
The scanner maintenance should be run whenever you suspect that copies are losing 
image quality due to the scanner maladjustment or periodically (e.g. once a month), 
depending on:  
 
• Number of hours of usage 
• Types of original loaded (some originals dirt the glass plate more than others) 
• Variations of temperature and humidity 
 
 
 
 
 
 
 
 
 
						

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The touch screen provides the user interface to the system and connects the various 
elements of the system. 
 
The user interface is divided into three parts (see picture below):  
 
• The control section, with four main control tabs: Copy (from original to final 
output), Scan (for scanning to a file), Print (for printing from a file) and Setup 
• The preview window, where you can see how the image will look when printed 
• The toolbar, a set of command buttons at the bottom, used to start or stop various 
actions (e.g. see a preview image, start copying) 
 
Preview window                Control section 
 
 
 
Toolbar 
 
What you see on the screen may vary slightly depending on the printer installed. 
 
 
						

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The task of the printer is to place tiny drops of ink on the media (paper or other 
substrate) in order to form an image that corresponds to the data file received. 
 
 
 
Your HP Large Format Copier supports the printers defined in the product’s data sheet. 
 
Most of them are thermal inkjet printers, which means that little drops of ink are heated 
up to the boiling point and sent to the media. The amount of ink that reaches the media 
is controlled by the writing system of the printer (the printer’s controller) and depends on 
the type of media and desired print quality (e.g. coated paper accepts less ink than 
photo-gloss paper and Best quality mode requires more ink than Fast mode). 
 
This is why it is very important to tell your copier system which type of media you have 
loaded. 
 
The real amount of ink dropped may be different from the amount requested by the 
printer’s controller, due to unequal performance of the printheads: one printhead may 
drop 12 pl
4 while another may drop 14 pl, thus resulting in different final colors. 
Another nuisance is that different media lots may behave differently: one lot may allow 
more ink than others to reach the inner part of the substrate, thus resulting in “duller” 
(washed-out) final colors. 
 
                                       
 4 A picoliter is equal to one millionth of one millionth of a liter. It is similar to a nanogram of ink (one 
millionth of a milligram). 
Printheads
Ink drops 
Input image 
Printed image
Desired  
pixel color