IntroductionWhen drawing up a methodology for testing printers, the main question that arose was whether it was worth making it separate for different types of devices. Under common name Printers actually hide devices that are quite different in capabilities and purpose. An attempt to find and apply a universal cure for all diseases does not always lead to success - the patient may die. Nevertheless, the desire to adhere to some common standards and a unified approach to testing peripheral devices in this category ultimately prevailed, albeit with certain reservations. These, first of all, were restrictions on the types of printers that fall under the scope of this technique. We deliberately extended its effect only to color inkjet and laser printers, without adapting it to matrix and thermal sublimation printers, due to the specificity and low prevalence of such models on the Russian market. In principle, this document can be used as a guide in the future when testing monochrome laser printers, excluding from it the items regulating the determination of color rendering quality.
The methodology we created concerns mainly two most important characteristics of printers, which, of course, are print quality and productivity. Of course, there is a third indicator - the cost of the product, which worries all users, but it is not within the scope of this technique and is dictated by the seller of the product. We can only subjectively assess the correspondence of the price of the printer to its other characteristics we are considering. In addition to this, of course, there are other factors that influence the decision to purchase a particular printer.
Before moving directly to the testing methodology, let's say a few words about other aspects that we will take into account when considering the next model of a printing device. We are talking about the following parameters:
Specifications;
Printing technology;
Design;
Software;
Printer equipment.
There is no point in describing the above points in detail - most users who have more or less to do with printers understand what we are talking about.
Print quality
The “print quality” indicator is general in nature. In fact, it is formed as a result of the interaction of several components, which together make it possible to ultimately obtain a pleasing picture on a sheet of paper. The overall result will depend on printing technology, ink, paper, software and some other factors. Naturally, in our case the task is to control what we get at the output.One of the main factors that determines a high-quality image is the printer’s ability to provide correct color reproduction. Let’s immediately make a reservation that we are talking specifically about the technical side of this issue, and not about the most beautiful and pleasant-looking image. As a result of its work, the printer must print an image that is as close as possible to the electronic original in three color components (RGB) in each pixel. Here it would be appropriate to recall that, of course, a finished color copy in practice is always worse than the original, since it is almost impossible for a printer to absolutely accurately convey the entire range of colors of the original. In addition, an important element in the operation of any printer is the ability to provide high-quality transmission of halftones. In some cases, the printer’s inability to provide uniform color fill throughout the entire brightness range becomes problematic for performing this task. Usually the most problematic areas are very light-colored areas. In color printing, black is formed by mixing RGB colors, and the final result is not always satisfactory due to the violation of their correct balance. Another aspect of obtaining a high-quality image on paper is the resolution of the printer, which allows for the correct transmission of the smallest details. Many modern printers have a very high print density declared by manufacturers, which in practice does not always have a direct relationship with the actual physical resolution, and the true state of affairs can only be determined through testing.
Now that we've looked at the problems that arise when trying to achieve maximum print quality, it's time to choose ways to specifically implement the task before us.
The resulting prints are evaluated subjectively and objectively. The first method is based on the traditional visual method, which allows you to identify defects visible to the naked eye. The second method is based on a more accurate and impartial assessment of print quality. It consists in the fact that printed test images are scanned on a reference scanner and converted into digital form. Next, using special software, RGB indicators are taken from special “plates”, and the degree of deviation in color characteristics from the original image is determined. In order to take into account the degree of error in the results introduced by the scanner itself, it is calibrated before testing using a proprietary Kodak Q-60 color target.
The above methods for assessing print quality fully apply to test images of color printing. If you use only black ink for printing, the procedure for testing prints is somewhat simplified due to the fact that there is no need to study color characteristics.
Print speed
All manufacturers indicate the printing speed in the documentation for their printers. The data given in the specifications refers to various operating modes and is expressed in the number of pages printed per minute. However, not all so simple. In theory, if manufacturing companies have a unified approach to determining speed for all models, the numbers should be quite correct, but as you might guess, there is no certainty that when determining print speed, all companies use the same reference documents. . In order to compare printers from different companies in terms of printing speed, it is better to conduct your own testing. IN such a case we use the same templates to determine the performance of all models, regardless of their affiliation with one company or another, and we will be able to make reasonable comparisons between them based on this indicator.To determine the printing speed, we will use three pre-prepared electronic layouts displayed on A4 sheets. The first of the templates is one page of text. The second layout consists of a combination of text and color graphics. In the first two cases, standard office paper (80 g/m^2) is used for printing. As the third layout, we use a color test image prepared by us, printed on photo paper best quality recommended by the manufacturer. In this case, the print mode is selected with the highest possible density. The printing time in all cases is recorded from the moment the Print command is issued until the sheet comes out into the tray.
Basic tests
The list of basic tests includes those that subsequently allow us to compare the quality and speed of printing of any printer models when they perform the most characteristic functions. For ease of comparison final results A3 and A4 printers use the same paper size. List of main tests:- Test for quality (speed) of color printing (office and photo paper A4). The file used is TF1 (description of the files used below).
- Monochrome print quality test (A4 office paper). The file used is TF3.
- Monochrome printing speed test (text, A4 office paper). The file used is TF4.
- Mixed printing speed test (b&w text/color graphics, A4 office paper). The file used is TF5.
- Monochrome printing resolution test (A4 office paper). The file used is TF2.
- Color printing resolution test (A4 photo paper). The file used is TF2.
- Test for moisture resistance of ink on paper after the print has dried (wet cotton wool).
Additional tests
In addition to the above-mentioned basic tests for print quality and speed, based on studying the ability of printers to perform their main functions, it is possible to conduct additional tests based on the specific capabilities of specific models. The point is that some printers allow you to print on CDs, roll paper, thick media, etc. and so on. Additional tests allow you to evaluate the quality of such functions. The feasibility of conducting additional tests will be decided based on the results of studying the characteristics of the printers included in the testing.Notes on the testing procedure
Now let's talk about how the testing itself is carried out. Before it starts, the printer heads are calibrated. If certain printer models require the installation of an additional cartridge to obtain a photorealistic image, then a similar step is taken. The printing mode is carried out with the “default” settings, in the absence of any comments in the text. The final testing parameters are selected depending on the specific characteristics of the devices under consideration.Test template files
TF1 fileIn order to determine the ability of printers to efficiently perform color printing, a special target was created. It features several color and one black and white artistic image, serving for subjective quality assessment.
In addition, on the target there is a rectangle with a gradient fill of black color from 0 to 100 percent, as well as a seven-color plate with “steps” of varying intensities and known values RGB. With their help, you can objectively assess the degree of correctness of color rendering of printers.
TF2 File
This test file in PDF format is intended to determine the resolution of printers. The USAF 1951 test image can be used to determine printer resolution. On this target there are several groups consisting of six elements each. The elements in each group are progressively smaller and numbered from one to six. Each element in the group is represented by two triples of rectangles located vertically and horizontally. Each a new group elements are smaller in size than the previous one. The level of nesting of groups is quite large and allows you to find out the maximum print resolution that the printer is capable of.
TF3 file
Intended for determining the quality of monochrome text printing, a doc-format file consists of several dozen lines of font of various sizes and styles, which also allows you to determine, to some extent, the maximum resolution.
TF4 file
This template is designed to determine the speed of monochrome text printing. A doc file contains one page of text in Times font. New Roman 10 points in size with regular style and single line spacing.
TF5 file
In order to determine the printing speed of mixed documents (monochrome text/color graphics), a file in doc format is used. It contains text in 10-point Times New Roman font with regular style and single line spacing and two color images (diagrams).
Assessment of color rendering quality based on objective indicators
When assessing the color rendering quality of a printer, we will to some extent adhere to the principles methodological approach described in the article about testing scanners.The image of the printed target (TF1 file), digitized after scanning in color mode with the optical resolution of the scanner, is used to determine the RGB color components at certain points using special programs, for example, Adobe PhotoShop. To do this, the results are taken on all eleven “sites” of different brightness of seven color “rulers”: Red, Green, Blue, Black, Yellow, Magenta, Cyan.
Next, all received data for each control point from the scanned image is entered into a special table.
Based on the results for all seven colors, the integral coefficient of correctness of the printer’s reproduction of original colors is determined. It is calculated as the sum of the difference, taken modulo, of the color component (RGB) values of each of the control points in the scanned image and the reference file, then divided by seventy-seven.
Lowest value, obtained as a result of calculations, will be a sign of the most accurate transmission color palette original by a printer from among those who took part in testing. Note that the indicator we propose is only suitable for comparative analysis quality of color rendition between models and cannot be an absolute assessment.
Color balance and halftone quality
Based on the measured RGB values of a rectangle with a gradient fill in black, a graph is constructed that reflects the quality of the printer’s performance of this procedure. The X axis is the distance expressed in pixels, and the Y axis is the RGB values of the pixels.The final picture in the case of close to ideal looks approximately the same as can be seen on the graph. The lines from all three black RGB components merge into a single whole, and the absence of dips and peaks indicates their balance. The desired range of color component (RGB) values should be from 0 to 255.
We will consider our methodology a basic document available for modification and development as it is applied in practice.
For printers: With the printer turned off, press the “Sheet” button without releasing it, press the “on” button, release it, continuing to hold the “Sheet” button for 10 seconds.
For MFP without monitor: the same process, only instead of a “sheet” there is a “Stop” button (triangle in a circle)
For with monitor: in the tab “Installation” - “Maintenance” - “Checking the nozzle” - “start” - “print”.
Printing a test page without a PC
Have you purchased a brand new printer? In any case, you will need to print test pages to check print quality. It’s good if the printer is connected to a computer through which you can start this process. What if this is not possible? How to print a test page without a computer? Let's figure it out.
So, the following tips will be useful for many modern devices. Start by loading regular white sheets of paper of the appropriate size into the input tray.
The print test page for inkjet printers is printed as follows: turn off the device with the button, press the “Sheet” button without releasing it, press the “ON” button, release it, continue to hold the “Sheet” button for about 10 seconds.
For Canon printers: hold both buttons (in in this case Resume button and ON button) until the power indicator lights up. After that, hold down the ON button, release and press the Resume button twice, release both buttons. After this, the readiness indicator will light up, which will signal the service mode. To print a test sheet, press Resume once, confirm the action with the ON button.
Printing a test sheet for a multifunction without a display: a similar process, only instead of the “Sheet” button there is a “Stop” button (triangle in a circle)
Test page for inkjet printing with multifunctional equipment equipped with a display: select the “Installation” tab, then “Maintenance” - the “Nozzle Check” menu - “Start” and “Print”.
When testing computer components and related solutions, we, of course, could not ignore such a class of devices as office equipment. Today it has become an indispensable attribute of any office or company with a large document flow. And it’s now difficult to imagine a modern home setup without a printer or MFP, especially if its owner is a schoolchild or student. As you can see, the scope of application of devices of this kind is quite extensive, and it covers both the corporate and SOHO market segments. In this regard, store shelves are literally littered with a variety of office equipment: from compact photo printers to professional office “harvesters”.
Naturally, such diversity can confuse even knowledgeable person, not to mention those who are faced with purchasing a printer or MFP for the first time. We hope that this technique and the series of materials prepared on its basis will help you understand the variety of models in order to make the right choice in the future.
First, we will briefly describe the structure of the review of a printer or MFP, and then we will talk in more detail about the testing itself. As always, for better understanding, the material will be divided into several sections.
Introduction and Specification
At the very beginning of the article, the relevance of the tested solution, its positioning in the model range, as well as how the manufacturer himself sees its use are described. Right there you can find the most complete specification of the device, compiled on the basis of information from official sources. In the future, during testing, we will definitely check to what extent the stated information corresponds to reality.
Packaging and delivery
In this section Special attention Let's pay attention to the packaging in which the printer is supplied. In particular, its dimensions, strength, design and information content. We will also take a closer look at the delivery package to see if the manufacturer has saved on any components.
Appearance and operating features
This section will be the most extensive. In addition to photographs of the tested solution with different angles, it will include detailed description all its key nodes. We will pay special attention to the operating features of the printer and MFP. “What paper sizes are supported?”, “How does the printing process work?”, “How do the trays and automatic feeder function?”, “Is it difficult to change the cartridge or ink?”, “What interfaces is the device equipped with?”, “Does it have any then additional functionality? − We will try to give the most complete and detailed answers to all these questions.
Consumables
Here you will find information about printer consumables that are used during printing. Depending on the type of device, these can be toner cartridges, ink containers or CISS. If possible, we will share information about their resource, cost of refilling and complexity of maintenance.
Autonomous operation
Professional or pretending to be such models can often function in standalone mode, that is, without connecting to a PC. If such an opportunity is present, we will definitely explore it in practice and describe our impressions in the “Autonomous operation” section.
Software
At this point the emphasis will be on software: driver capabilities, number of settings and available functionality.
Testing
Finally, we come to the most interesting part - the process of testing the capabilities of the device. The procedure itself will be divided into several series of experiments, so we decided to divide this section into several subsections. By following this link, you can download the original documents and images that are used in the testing process.
First page out time
The first page out time is the first way to evaluate how quickly a printer processes a job. The experiment is carried out in two modes: on a warm (ready to print) and cold device. In the second case, part of the time is spent preparing the printer for operation (exiting energy saving mode, warming up, etc.).
A page of plain text saved in DOC format will be sent for printing. In this case, the printer driver sets the maximum print quality.
Print speed in monochrome mode
To evaluate the printer's printing speed in monochrome mode, we prepared four scenarios:
"Text" − a 20-page document saved in DOC format, with text typed in Times New Roman 10-point font, and different types formatting.
"Text + drawings" − a 10-page document saved in DOC format, with half-sheet drawings and text in Times New Roman 10-point font.
"Text in vector format" − a file in vector format (CDR), which consists of one page of text typed in Times New Roman and Arial fonts with different font sizes.
"Photo" − black and white photography high resolution, saved in PDF format.
These scripts are run for each print mode available in the driver menu. In all cases, the printer warms up in advance. If the device has the ability to duplex print (on two sides of paper), then similar tests will be carried out for this mode. For the purity of the experiment, ordinary office paper with a density of 80 g/m2 is used, which can be bought at any office supply store.
Then the data is entered into a table, the estimated print speed for each mode is determined, and based on the information received, certain conclusions are drawn.
Color print speed
Five different types of photographs are printed one by one (the principle of their selection is described in more detail in the subsection “Evaluating the print quality of photographs and vector elements”) and the time it takes for the page to come out of the tray is measured. We will conduct the test by pre-heating the printer and selecting the maximum print quality in the driver menu. During the experiment, again, ordinary office paper with a density of 80 g/m2 is used, and for professional devices, special photo paper is also used (its properties will be discussed separately in each case).
Assessing the quality of text printing
A document saved in vector CDR format is launched for printing, with a set of control fonts (Times New Roman and Arial), typed in different sizes. Based on the finished print, it will be possible to determine the presence of grain, the degree of filling of characters, the accuracy of drawing serifs on letters, as well as minimum size readable font. Again, the experiment is run for all modes available in the driver menu.
Assessing the print quality of photographs and vector elements
This group of tests is more relevant for photo printers. However, they will also run on regular monochrome devices. This way, we will be able to comprehensively evaluate the capabilities of all solutions that come to us for testing, and in the future draw more objective conclusions when comparing models from different price ranges.
Please note that the process of selecting photographs did not occur spontaneously. Pictures contain a variety of effects, so if the printer distorts the gamma somewhere, reproduces colors incorrectly, “washes” the picture or makes it unclear, this will immediately appear on the prints. Images No. 1 - No. 6 are presented in PDF format, and No. 7 are in vector CDR format.
Image #1. Checking the accuracy of rendering shades of gray and drawing hair. “Sharp” transitions between white and black backgrounds will help reveal how much the printer “clogs” the image at the boundaries of objects.
Image #2. Checking the accuracy of dark shades. If the printer makes the image too contrasty (increases the gamma), the details of the scene in the shadows will be poorly visible or will not be drawn at all.
Image #3. Checking the accuracy of light shades and bright objects. At the end, the picture should not be dull, and the sky, sand and water should merge into one.
Image #4. Checking the quality of drawing of metal and shiny surfaces.
Image #5 . Checking the print quality of HDR photos. Ideally, the resulting colors should be just as saturated, without turning into warm or cold shades. Also, using this image, you will be able to check how accurately the printer is able to convey the reflection of objects on the car body and the texture of asphalt chips (the road should look three-dimensional, and not a piece of gray plywood).
Image #6. Checking the accuracy of human skin tone. The print will immediately show whether the photo printer corresponds to its status or whether it wears the “photo” prefix only for advertising purposes.
Image #7. Checking the accuracy of the output of gradient fills, thin lines and the quality of green color synthesis. Four gradient stripes correspond to the primary CMYK colors. They are formed by using a 512-step vector fill. The presence of vertical stripes here will indicate that the printer has problems with accurately transmitting gradients. Radial stripes and a “star” with a spiral in the center are drawn with a line one pixel thick. Printing these elements is quite a difficult task for printers. Note that some of the lines are drawn green. Thus, we get the opportunity to evaluate the accuracy of the formation of this shade by mixing yellow (Yellow) and turquoise (Cyan) paint. The group of lines located in the lower corner is intended to check the quality of color synthesis at the intersection of these lines.
Operating the device in scanner mode (if such a feature is available)
The photographs pre-printed on professional equipment, which were discussed in the previous section (images No. 1 - No. 6), are scanned. This procedure is repeated for each type of resolution available in the driver menu. After the experiment is completed, the resulting prints are compared with the originals and appropriate conclusions are drawn.
Operating the device in copier mode (if this option is available)
One page of text and the same photographs (images No. 1 - No. 6) are copied at different quality settings. In each case, the page output speed is measured after pressing the “Copy” button, and the resulting prints are also compared with the originals.
Energy consumption
Energy consumption will be measured both while the device is operating (printing, scanning, copying) and in idle mode (sleep).
Additional features
Sometimes manufacturers equip printers and MFPs with additional modules, for example, network interfaces or slots for memory cards. In principle, this does not apply to the main functionality of office equipment, but potential buyers will certainly be interested in how these units perform in practice.
Results
In our opinion, the set of tests presented in this methodology is quite enough to fully reveal the potential of a printer or MFP and draw certain conclusions. In each review we plan to publish links to scanned prints that were received during testing. This way you can evaluate the quality of printing (scanning, copying) not only from our words, but also personally, according to some of your own criteria. In other words, using this technique we will try to give readers as much information as possible to form an objective picture of the capabilities of office equipment that will end up in our test laboratory.
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To evaluate the quality of inkjet ink, three types of test pages: TF1, TF2 and TF3.
TF1 test page used to test the quality of color inks. It allows you to analyze the ability of the ink to produce accurate color reproduction of shades and halftones.
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Sample TF1 test files
The TF1 test page is printed on standard A4 paper. It is a collection of monochrome and color images, multi-colored square “dies” and areas with a gradient fill from zero to one hundred percent.
Using the TF1 test page, you can objectively evaluate both the color rendition of any one inkjet ink, and organize comparative testing of several types of inks.
To determine the color rendering quality of inkjet inks, the resulting TF1 test pages are digitized using a color scanner. The resulting files are used to define RGB components in certain areas of the page. To do this, using graphic editor Adobe Photoshop The result of transmitting the primary ink colors is recorded, and the received data is entered into the color table. The resulting table allows you to determine the coefficient of correct reproduction of ink of various colors and shades. This coefficient is calculated using the formula:
Formula for determining the correctness coefficient
The lower the coefficient of correctness of reproduction of colors and shades, the more accurate color reproduction will be provided by inkjet printer ink.
The data obtained when checking the color rendering quality of inkjet ink allows us to construct a graph in which we plot the distance on the X-axis, and pixel values on the Y-axis. We connect the dots and get a single line, the dips and peaks on which indicate an unbalanced color rendering. If there are no dips or peaks, then the color rendition is balanced. The recommended range of deviations of RGB values should not exceed 255.
The next test page that is used to evaluate the quality of inkjet ink is the TF2 page.
TF2 test page
TF2 test page is a PDF file consisting of several groups of elements, which, in turn, include six independent parts, located vertically and horizontally. Groups of elements on the TF2 test page are numbered, with each previous element slightly larger than the next. The quality of printing is the most small elements test page determines the resolution of inkjet ink.
TF2 test pages are used to test monochrome and color inkjet inks. TF2 pages are printed on A4 paper. In this case, when testing monochrome inks, standard office paper is used, and when testing color inks, photo paper is used.
The third type of test pages are TF3 files, used to determine the quality of black monochrome inks.
The ideal test sheet. This example shows what a flawless print should look like.
Repetitive black dots located vertically on a white test sheet. This test sheet characterizes the most common type of defect - a point breakdown of the photolayer of the photodrum. Breakdowns come in different diameters: from barely visible points to greasy spots. In this case, there is a need to completely replace the photodrum, since there is no technology for its restoration. This decision is made depending on the client’s requirements for print quality, since small pinholes when printing only text are practically indistinguishable and there is no need to replace the photodrum. But over time, the dots increase in size. Then it will be possible to think about replacing such an important component.
Defective magnetic shaft. A vertical stripe on the black test sheet indicates the presence of a scratch on the magnetic shaft, which is a defect. In this case, the magnetic shaft must be replaced, since the light stripe significantly degrades the quality of printing text and pictures.
Solid vertical black stripe on a white test sheet. The appearance of a continuous or intermittent vertical one black or several stripes along the edges of the white test sheet indicates serious damage to the photo layer on the drum. Otherwise, such drums are called “burnt”. These defects are clearly visible to the naked eye. The photolayer at the site of damage has a characteristic Brown color or if absent, exposes subsequent layers. The photoconductor must be replaced. On a black test sheet with such defects, a broken stripe is visible along the edge.
An example of Samsung and Xerox cartridges being defective. They differ from defects on HP and Canon cartridges due to differences in the technological device. Spots on both test sheets, vertical stripes on the black test sheet and repeating horizontal dots on the white indicate the need to replace the large rubber shaft, photoconductor.
The toner is running low. The photo shows what the test sheet looks like when the toner cartridge runs out. This is especially noticeable on the black test sheet. This example is not a defect. It's just time to refill the cartridge.
Smears and waves on light dough. The appearance of streaks and waves on the light dough indicates improper storage of the cartridge, as a result of which it has become damp. In this case, the consumable must be cleaned of old toner and refilled.
Vertical stripe, pale print. The paleness of the print and a clearly visible vertical stripe on the black test result from scratches on the magnetic shaft, as well as its severe wear. The same signs appear when the photodrum is burnt out. To improve print quality, it is advisable to replace worn and damaged components.
Toner is stuck to the squeegee. Sometimes, toner may stick to various parts of the cartridge due to increased temperatures in the printer during operation, significantly degrading print quality. It is necessary to clean the squeegee and remove excess toner from the parts.
We talked about the main defects of cartridges and their impact on print quality.