3.3 Digital Image
Analysis (Reflection
Measurement)
This methodology has been applied to characterize the color of
tomato products and to estimate lycopene levels, as compared to
spectroradiometry [39] (see Note 8).
1. Connect plug power adaptor to the cabin.
2. Switch the lamps on by pressing twice the “Enter” button.
3. Wait for 10 min for light stabilization.
4. Select the diffuse or direct light by means of the action of the
two handles located at the ends of the lower part of the cabin.
5. Turn on the computer and run the “DigiEye” software.
6. The grey table must then be removed from the tray and the
calibration chart is placed instead on the protrusions on the
surface of the tray.
7. An image of the chart is made in the menu
“Camera” ! “Release” ! “Release”.
8. Then select the menu “Calibration” ! “Camera”.
9. A pop-up window will ask if the marks are on the colored
frames. After making sure and accepting, a graph and values
will appear. These values show in terms of color differences
(CIEDE 2000) the difference between the measured units and
what is stored by the software. The average must be less than
1.5 and the median less than 1.2. If the lamps and the calibration chart are in good conditions this process does not have to
give error.
10. From this moment on, the camera is calibrated, and it is
possible to make the desired images of the samples. To do
this,
click
again
on
the
menu
“Camera” ! “Release” ! “Release” (see Note 9).
11. In the top menu there are selection tools like an image editing
program. Select one of the different tools and select the desired
area by dragging the mouse (see Notes 10 and 11).
12. Once the area has been selected, press the “DigiPix” menu,
select below the sample from where you want to acquire the
data (S1, S2, S3, ...) and press “Reflectance” (see Note 12).
13. In a pop-up window a graph will appear with the reflectance
spectrum of the marked area and below, the colorimetric coordinates according to the type of illuminant.
14. The images can be also saved as TIF or JPG formats in the
menu “File” ! “Save”.
15. From the carotenoid content determined by analytical techniques and the colorimetric parameters measured by Digital
Image Analysis, look for statistical models that allow to estimate the carotenoid concentration in other samples from the
color measurements.
Applications of Visible Spectroscopy and Color Measurements in the. . .
113
Analysis (Reflection
Measurement)
This methodology has been applied to characterize the color of
tomato products and to estimate lycopene levels, as compared to
spectroradiometry [39] (see Note 8).
1. Connect plug power adaptor to the cabin.
2. Switch the lamps on by pressing twice the “Enter” button.
3. Wait for 10 min for light stabilization.
4. Select the diffuse or direct light by means of the action of the
two handles located at the ends of the lower part of the cabin.
5. Turn on the computer and run the “DigiEye” software.
6. The grey table must then be removed from the tray and the
calibration chart is placed instead on the protrusions on the
surface of the tray.
7. An image of the chart is made in the menu
“Camera” ! “Release” ! “Release”.
8. Then select the menu “Calibration” ! “Camera”.
9. A pop-up window will ask if the marks are on the colored
frames. After making sure and accepting, a graph and values
will appear. These values show in terms of color differences
(CIEDE 2000) the difference between the measured units and
what is stored by the software. The average must be less than
1.5 and the median less than 1.2. If the lamps and the calibration chart are in good conditions this process does not have to
give error.
10. From this moment on, the camera is calibrated, and it is
possible to make the desired images of the samples. To do
this,
click
again
on
the
menu
“Camera” ! “Release” ! “Release” (see Note 9).
11. In the top menu there are selection tools like an image editing
program. Select one of the different tools and select the desired
area by dragging the mouse (see Notes 10 and 11).
12. Once the area has been selected, press the “DigiPix” menu,
select below the sample from where you want to acquire the
data (S1, S2, S3, ...) and press “Reflectance” (see Note 12).
13. In a pop-up window a graph will appear with the reflectance
spectrum of the marked area and below, the colorimetric coordinates according to the type of illuminant.
14. The images can be also saved as TIF or JPG formats in the
menu “File” ! “Save”.
15. From the carotenoid content determined by analytical techniques and the colorimetric parameters measured by Digital
Image Analysis, look for statistical models that allow to estimate the carotenoid concentration in other samples from the
color measurements.
Applications of Visible Spectroscopy and Color Measurements in the. . .
113