KYOTO UNIVERSITY京都大学

Effectiveness of PL Filtering Image with Halogen Lamp for Agricultural Products

KYOTO UNIVERSITY京都大学

Problems on image acquisition

Halation Surrounding walls reflection

KYOTO UNIVERSITY京都大学

Cuticular layer of apple fruit

Cuticular layer

Epidermis

ParenchymaHalation

KYOTO UNIVERSITY京都大学

Objectives

• To investigate relation between cuticular layer and fruit surface gloss

• To investigate effectiveness of PL filtering image compared with conventional dome and diffuser-used images

KYOTO UNIVERSITY京都大学

Dome or diffuser

Diffuser

HalationWall reflection

Light

Camera

Reflection plate

Indirect lighting devices (Dome and Diffuser)

KYOTO UNIVERSITY京都大学

Direct Lighting Device with PL filter

PL filter Heat absorption filters

Fan(more than 1000nm)

(800～1000nm)

Halogen lamp

PL filtering

Light

CameraPL filter

True color

PL filter

KYOTO UNIVERSITY京都大学

Comparison of lamps

Price Low Low Mid High High

Halogen Incandescent Fluorescent LED HID

Brightness High Mid Low Low High

Color rendering High High Low Mid Mid

Lumen High High Mid High LowMaintenanceLife Mid Short Mid Long Long

KYOTO UNIVERSITY京都大学

Direct lighting device with LEDs

120 white LEDs

Easy control: Quick Response for input signal

KYOTO UNIVERSITY京都大学

Lighting Device ArrangementArrangement 1(Dome walls and 4 DLs)

Arrangement 2 and 3(Diffusers or PL filters and 4 DLs)

KYOTO UNIVERSITY京都大学

Materials

• category 1 (glossy surface fruits: apples, tomato, eggplant, pepper, lemon)

• category 2 (short hair fruits or powdery fruits:

kiwi, peach, pear, banana)

• category 3 (root vegetables: potato, Daikon radish)

KYOTO UNIVERSITY京都大学

Category 1 (Smooth and thick cuticle)

Walls of dome

Dome Diffuser PL filter

Apple

Eggplant

KYOTO UNIVERSITY京都大学

Category 2 (Rough cuticle)

Dome Diffuser PL filterPeach

Pear

KYOTO UNIVERSITY京都大学

Category 3 (No cuticle)

Dome Diffuser PL filter

Daikon radish

Potato

KYOTO UNIVERSITY京都大学

Relation between degree of gloss and cuticular layer thickness

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120

Thickness of cuticular layer (pixel)

Degr

ee o

f gl

oss

potatoradish

banana

lemon

eggplant

pepper

apples

pear

peach

tomato

Category 1

Category 2

Category 3

(100 pixels is almost 25 μm.)

Degree of gloss: SD within twice area of halation

KYOTO UNIVERSITY京都大学

Images on different exposure conditions

Dome Diffuser PL filter

Exp.1(dark)

Exp.2(mid)

Exp.3(bright)

KYOTO UNIVERSITY京都大学

HSI on different exposure conditions

Dome Diffuser PL filter

Exp.1(dark)

Exp.2(mid)

Exp.3(bright)

KYOTO UNIVERSITY京都大学

Hue

Exp.1(dark)

Exp.2(mid)

Exp.3(bright)

Dome Diffuser DL with PL filter

KYOTO UNIVERSITY京都大学

Hue on different exposure conditions

(Average hue value change except too bright and too dark pixels)

300

310

320

330

340

350

360

370

Exp.1(dark) Exp.2(midium) Exp.(bright)

Diffuser

Dome

PL

KYOTO UNIVERSITY京都大学

Saturation

Exp.1(dark)

Exp.2(mid)

Exp.3(bright)

Dome Diffuser DL with PL filter

KYOTO UNIVERSITY京都大学

Saturation on different exposure conditions

0

20

40

60

80

100

120

140

160

180

200

Exp.1(dark) Exp.2(midium) Exp.(bright)

Diffuser

Dome

PL

(Average hue value change except too bright and too dark pixels)

KYOTO UNIVERSITY京都大学

Conclusion

• Degree of gloss (halation) on fruit had proportional relation with thickness of cuticular layer.

• PL filtering image had higher color reproduction compared with diffuser or dome.

• Dome made larger low saturation area.