CN110648321A

CN110648321A - Method for evaluating uniformity of temperature inside oven

Info

Publication number: CN110648321A
Application number: CN201910906550.2A
Authority: CN
Inventors: 王聪会; 杨建华; 石静
Original assignee: Northwest University of Technology
Current assignee: Northwestern Polytechnical University; Northwest University of Technology
Priority date: 2019-09-24
Filing date: 2019-09-24
Publication date: 2020-01-03

Abstract

The invention provides an oven temperature uniformity evaluation method, which adopts a digital image processing technology to analyze baked food images, shoots digital images of the baked food images, analyzes and extracts color characteristic values of the baked food images, digitally expresses different baking states, defines uniformity evaluation coefficients of the baked food images and further reflects the uniformity of the temperature in an oven. Preprocessing the image of the baked food, wherein the preprocessing comprises the following steps: filtering to reduce image noise, removing background, and preprocessing the image; analyzing and extracting a color characteristic value of the baked food image; performing mesh division on the preprocessed baked food image according to the shape of the baked food; the uniformity evaluation coefficient of the baked food image is defined based on the grid division method, the uniformity of the baked food is evaluated according to the uniformity evaluation coefficient, and the uniformity of the baked food is analyzed to further reflect the temperature uniformity inside the oven. The method has the advantages of simple process, easy operation, easy popularization and very wide application prospect.

Description

Method for evaluating uniformity of temperature inside oven

Technical Field

The invention relates to the technical field of daily necessities, in particular to an evaluation method for temperature uniformity inside an oven.

Background

With the popularity of baking culture, the popularization and popularization of baking and baked food drive the vigorous development of household oven product markets. A welcome household oven not only needs to have innovative shape and comfortable user interaction experience, but also can bake food with excellent, fragrant and delicious taste, and brings good cooking experience. One of the key contributing factors is the uniformity of the temperature field distribution inside the oven. The distribution characteristics of the temperature field inside the oven directly affect the quality of the baked food.

In view of the current research situation, the research method of the temperature distribution characteristics of the oven is relatively single, only the measurement and prediction of specific values of the temperature points tested in the oven are focused, and the effect of the temperature in the oven on the quality of baked food is not directly reflected.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides an oven temperature uniformity evaluation method which is characterized in that the uniformity of an image of baked food is represented by adopting a set uniformity evaluation coefficient of the image of the baked food based on the processing analysis of the image of the baked food, and further the uniformity of the temperature in an oven is further reflected by the action of the temperature in the oven on the baked food. The method has the characteristics of simple operation, good stability, high working efficiency, easy realization and no damage to the oven.

The technical scheme of the invention is as follows:

the method for evaluating the temperature uniformity of the oven is characterized by comprising the following steps of: the method comprises the following steps:

step 1: for a plurality of ovens needing comparative evaluation, a plurality of pieces of food to be baked are manufactured by adopting the same manufacturing materials and manufacturing process, and the food to be baked is processed by adopting the same baking parameter setting through the ovens, so that a plurality of pieces of baked food are obtained;

step 2: shooting images of the baked food under the same shooting conditions;

and step 3: filtering and denoising the plurality of baked food images obtained in the step 2 and removing background areas to obtain pure baked food images;

and 4, step 4: carrying out color characteristic analysis on each pure baked food image, extracting the L value of each pixel point in the image, and then taking the mean value of the L values of all the pixel points in the image as the mean value of the color characteristic values of the pure baked food image

And 5: according to the number of food blocks in the baked food, carrying out grid blocking on the pure baked food image by adopting a grid, wherein the number of the grid blocks is the same as that of the food blocks, and the baked food is arranged in each grid block;

step 6: for each grid block in each pure baked food image, taking the average value of L values of all pixel points in each block as the average value of the color characteristic value of the block

And 7: calculating the oven temperature uniformity evaluation coefficient of each oven according to a formula

Wherein n is the number of grid blocks;

and 8: and (4) calculating an oven temperature uniformity evaluation coefficient of each oven needing to be compared and evaluated according to the step (7), wherein the lower the uniformity evaluation coefficient is, the more uniform the temperature distribution in the oven is.

Further preferably, the method for evaluating the uniformity of the temperature of the oven is characterized by comprising the following steps: and 3, reducing the image noise of the baked food by adopting bilateral filtering.

Advantageous effects

Compared with the prior art, the invention has the following advantages:

1. in the uniformity evaluation process, the method can be completed by means of image acquisition equipment and a computer, and is convenient and quick;

2. compared with the prior art that a simulation model which is matched with the actual model needs to be set, the method disclosed by the invention can digitally give the evaluation coefficient of the temperature uniformity of the oven without considering model building, and is high in precision and simple and convenient to operate.

3. The method analyzes the uniformity of the image of the baked food, and visually and intuitively reflects the effect of the temperature inside the oven on the baked food compared with the traditional method.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

fig. 1 is a schematic view of a baked food image according to an embodiment of the present invention.

Fig. 2 is a schematic diagram of a baked food after image preprocessing according to an embodiment of the invention.

Fig. 3 is a schematic diagram of gridding an image of baked food according to an embodiment of the present invention.

Detailed Description

The following detailed description of embodiments of the invention is intended to be illustrative, and not to be construed as limiting the invention.

The invention provides an oven temperature uniformity evaluation method which is based on processing analysis of baked food images, adopts a set baked food image uniformity evaluation coefficient to represent the uniformity of the baked food images, and further reflects the uniformity of the temperature inside an oven through the effect of the temperature inside the oven on the baked food. The method specifically comprises the following steps:

step 1: and for a plurality of ovens needing comparative evaluation, a plurality of pieces of food to be baked are manufactured by adopting the same manufacturing materials and manufacturing processes, and the food to be baked is processed by adopting the same baking parameter settings through the ovens, so that a plurality of pieces of baked food are obtained.

Step 2: under the same shooting conditions (such as light, relative distance between a lens and the baked food, and the like), the baked food is shot.

And step 3: and (3) performing bilateral filtering noise reduction and background area removal processing (such as baking trays and oil absorbing paper) on the multiple baked food images obtained in the step (2), and only reserving the baked food areas to obtain pure baked food images, as shown in fig. 2.

And 4, step 4: analyzing the preprocessed baked food image, evaluating color characteristic values capable of reflecting different baking states, and representing the baking states:

carrying out color characteristic analysis on each pure baked food image, extracting the L value of each pixel point in the image, and then taking the mean value of the L values of all the pixel points in the image as the mean value of the color characteristic values of the pure baked food image

And 5: according to the number of food blocks in the baked food, grids are adopted to perform grid blocking on the pure baked food image, the number of grid blocks is ensured to be the same as the number of food blocks, and the baked food is arranged in each grid block, as shown in fig. 3.

Wherein n is the number of grid blocks;

and 8: and (4) calculating an oven temperature uniformity evaluation coefficient of each oven needing to be contrastively evaluated according to the step (7), wherein the lower the uniformity evaluation coefficient is, the more uniform the image of the baked food is, and the more uniform the temperature distribution in the corresponding oven is.

In this embodiment, the color feature value mean value in each grid blockAs shown in table 1:

grid Block numbering	Mean value of color feature values
		1	59.74
2	62.60
		3	54.45
4	58.93
		5	65.66
6	57.49
		7	60.89
8	61.69
		9	52.10
10	55.90
		11	62.20
12	60.03

According to the average value of the color characteristic values of the respective grid blocks of the baked food given in table 1, the uniformity evaluation coefficient of the baked food image of fig. 1 can be obtained:

13.56 is regarded as the uniformity evaluation value of the baked food image of fig. 1. Correspondingly, for other ovens, the corresponding uniformity evaluation value is obtained by the method, and the lower the uniformity evaluation coefficient is, the more uniform the image of the baked food is, and the more uniform the temperature distribution in the corresponding ovens is.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made in the above embodiments by those of ordinary skill in the art without departing from the principle and spirit of the present invention.

Claims

1. The method for evaluating the temperature uniformity of the oven is characterized by comprising the following steps of: the method comprises the following steps:

step 2: shooting images of the baked food under the same shooting conditions;

Wherein n is the number of grid blocks;

2. The method for evaluating the uniformity of the temperature of the oven according to claim 1, wherein: and 3, reducing the image noise of the baked food by adopting bilateral filtering.