JPH04145770A - Deciding method for image quality in transfer photographic printing method - Google Patents

Abstract

PURPOSE:To obtain objective decision by a quantitative measurement by comparing color density level data of all unit picture elements with a normal level and calculating a void area, and deciding by a ratio of the void area and a measuring object region area. CONSTITUTION:With regard to a measuring object region, color density level data of each unit picture element of a transfer image generated on an image receiving sheet by supplying photographic printing energy of prescribed density is compared with a normal level set by a statistic processing result or a standard sample, and an area of the part of color density being under the normal level is calculated as a void area. Subsequently, by a ratio of the void area and the area of the measuring object region, the image quality is decided. In such a way, the image quality is measured quantitatively by a numerical value, and can objectively be decided.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] The present invention relates to a method for quantitatively determining image quality in a transfer printing method.

[Prior Art] In the transfer printing method, a transfer sheet having a colorant layer and an image receiving sheet are overlapped, and printing energy (
A transferred image is obtained on an image-receiving sheet by supplying energy (for example, thermal energy).

Conventionally, the method of determining the image quality of transferred images obtained by transfer printing methods, that is, the image quality of transferred prints, is to visually observe abnormal transfer conditions such as uneven density and missing or missing dots forming the image. , a method for determining image quality is used.

Image quality is determined by the materials used in the transfer printing method, such as transfer sheets (for example, ink transfer sheets) and image-receiving sheets (for example, printing paper or image-receiving paper), as well as the printer's orgy supply means for transfer, such as thermal heads. It is important to quantitatively measure the image crystallization of transferred prints and determine the trend, as it depends on the quality of the hardware configuration, such as the control of the laser beam and the control of the laser beam. It has become an important indicator for confirming gender.

[Problems to be Solved by the Invention] However, in the conventional method of visually judging the image quality of transferred print C, the environment in which the sample to be judged is visually observed (
The criteria for judging image quality can vary greatly depending on factors such as temperature, humidity, light source conditions, etc.), the physical condition of the visual judge, the image of the sample to be judged at that time, and the second condition of the previously visually inspected sample. In particular, for samples to be judged with only a slight difference in image quality, the judgment may vary each time the judgment is made.

Furthermore, the judgments made will change even if different judges perform visual inspections, and in the end only samples with large differences will be able to obtain reliable judgments. It was impossible to judge the image quality of transferred prints.

As a result of extensive research, the inventors of the present invention have focused on the fact that unevenness in density that occurs in transferred prints, chipped or missing dots that form images, etc. degrade image quality. The present invention was completed based on the idea that quantification and judgment can be made by measuring the degree of chipping, omission, etc. of dots forming an image and converting it into numerical values.

That is, an object of the present invention is to provide a method for quantitatively measuring and objectively determining the image quality of a transferred print.

[Means for Solving the Problems] Therefore, the gist of the present invention is to superimpose a transfer sheet having a colorant layer and an image-receiving sheet, and supply printing energy to the back side of the transfer sheet. In a transfer printing method that involves obtaining a transferred image, in order to judge the image quality of the transferred image, at least the area to be measured is determined by: (b) Processing the obtained transferred image with an image processing device to obtain color density level data for each unit pixel of the processing; (c) Color density level data for a plurality of transferred images. (d) Setting the color density level that should be obtained with the printing energy of the constant density as the normal level based on the statistical processing results or the complete color density standard sample; (e) Calculate the area of the area of the color density below the normal level as the area of the white area when compared with the normal level; A method for determining image quality in a transfer printing method, characterized by comprising the following steps:

The present invention will be explained in detail below.

First, the basic idea on which the present invention is based will be explained.

As mentioned above, image quality can be judged by measuring the degree of unevenness in image density and missing or missing dots that form an image. , omissions, etc. are considered to be the result of ``colors not having the density they should be in the places they should be'', and [white areas where the normal color density is not colored] degrade the image quality of the transferred print. It is thought that the

Therefore, by measuring this F white portion J, it becomes possible to quantitatively express the image quality of the transferred print.

The method for calculating the area of the "white part where the normal color density is not colored" of the sample to be determined is basically the following (a).
It includes five steps of ~(e).

(a) A transferred image is obtained on an image-receiving sheet by supplying printing energy at a constant density to the back side of the transfer sheet.

(b) Processing the transferred image with an image processing device to obtain color density level data for each unit pixel of the processing.

(e) Set the normal level.

(d) The above data is compared with the normal level, and the area below the normal level is calculated as the area of the white area.

(e) Calculate the area ratio of white areas in the measurement target area (hereinafter referred to as "area ratio of white areas"); if the area ratio of white areas is small, the image quality is high; conversely, if the area ratio is large, the image quality is It is judged as low.

Although the specific procedure is not particularly limited, for example, it is as follows.

■ Keep the temperature environment constant and stable during sample preparation of printing machines, image receiving paper, etc., keep the pressure constant, and keep the printing start temperature constant and the printing temperature constant (preventing energy increase due to heat accumulation) ) to create a sample of the transfer print.

In particular, printing in a single color of magenta is effective when capturing images with a camera and in correspondence with visual inspection, but even with other colors or transfer prints with full-color images, it is difficult to print inside the measurement target area. If no energy density gradient occurs, it is valid as a sample.

The area to be measured is only a certain area of a certain place on the sample.
That is, it is extracted as a determination location and captured as an image into image processing equipment.

The captured image is recognized by unit pixels of appropriate size, and color density level data for each unit pixel is obtained.

■ ■ Based on the color density distribution graphs of multiple samples, for example, the peak level is set as the normal level. Or
If a complete and ideal color density standard sample exists,
The color density level is set as the normal level. Of course, other regular level setting methods may be used.

The color density data in each unit pixel is binarized using the normal level as a boundary, and the image is displayed in two colors. At this time,
It is better to perform negative processing so that areas with color density below the normal level remain black, as this makes area measurement easier.

The area of the white part (black part if negative processing is performed) after image processing, that is, the area of the white part, is measured.

■ The white area obtained is the ratio of the area to the area of the judgment location,
That is, for white areas, the area ratio is calculated.

The image quality of white areas is determined by the size of the area ratio. White lines are used when it is necessary to match the area ratio value to qualitative expressions of image quality (for example, "excellent", "good", "acceptable", "unacceptable", etc.). Exclusion can be determined empirically from data on the correspondence between numerical values of area ratio and visual judgment.

[Examples] Next, specific embodiments of the present invention will be explained in more detail using Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded.

The samples were prepared by using a dye-sublimation type transfer sheet and using one of various types of sublimation dye-receiving photographic paper (image-receiving paper).

The sample was created by applying a constant density of printing energy, keeping the pressure constant, keeping the printing start temperature constant, and controlling the printing energy after printing started, taking into account the heat storage effect of the thermal head. The transfer sheet was created by controlling the application of a constant amount of thermal energy to the back surface of the transfer sheet.

The following image receiving sheet was used.

No. 1 Photographic paper based on synthetic paper No. 2 Photographic paper based on paper (cellulose) with medium thickness of the dyed layer No. 3 Photographic paper based on paper (cellulose) Paper with a thick dyeing layer No. 4 Photographic paper based on paper (cellulose) with a thin dyeing layer No. 5 PET (polyethylene terephthalate) foam
Photographic paper No. 6 based on opalescent PET Each of the above image receiving sheets was used, and a monochromatic magenta was used as the transfer sheet, and a printing energy of 0.21 W/dot was supplied. A sample of the transfer print was created using the following methods.

A 4 mm x 15 mm area on the transferred image of each sample was used as the determination location, and 16 per 1 mm2 was placed in the image processing equipment (trade name MKSIPS, manufactured by Mitsubishi Kasei @ A particulate image analysis system was used as the image processing program).
The images were captured as images with a resolution of 0.00 pixels, binarized using the regular color density level for each sample, the areas of white areas were calculated, and the area ratios of white areas were calculated.

Table 1 compares the results with the visual judgment results using the conventional method.
Shown below.

As described above, the results of the determination based on the area ratio of the white areas obtained by the method of the present invention were in good agreement with the results determined by visual inspection.

The following effects were achieved [Effect of the invention] By the method of the present invention, Ta.

The image quality of transfer prints, which was previously judged visually, can now be expressed quantitatively using numerical values.

(2) Judgments are no longer influenced by the person making the judgment, the date and time, or the viewing environment.

(3) Subtle differences can now be judged objectively without being influenced by images.

(4) Accumulation of data and therefore analysis became possible.

Claims (1)

[Claims] (1) In the transfer printing method, which involves overlapping a transfer sheet having a colorant layer and an image-receiving sheet and supplying printing energy to the back side of the transfer sheet, a transferred image is obtained on the image-receiving sheet. In determining the image quality, at least for the area to be measured, (a) obtaining a transferred image on an image receiving sheet by supplying printing energy at a constant density to the back side of the transfer sheet; (b) using the obtained transferred image; Processing with an image processing device to obtain color density level data for each unit pixel of the processing; (c) From the statistical processing results of color density level data in a plurality of transferred images or from a complete color density standard sample, the above (d) comparing the color density level data of all the unit pixels with the normal level, and determining the portion of the color density below the normal level; A transfer printing method comprising the following steps: (e) determining the image quality based on the ratio of the white area to the area of the measurement target area. A method for determining image quality.