QUANT SOFTWARE TUTORIAL 1 General

Professor Dr. Francisco Xavier Ribeiro do Vale QUANT V.1.0.1 QUANTIFY PLANT DISEASE SEVERITY Software by: Professor Dr. Elpídio I. Fernandes Filho Time: Professor Dr. Francisco Xavier Ribeiro do Vale Universidade Federal de Viçosa (UFV), Departamento de Fitopatologia, Viçosa, MG, Brazil, CEP 36571-000 e-mail: dovale@ufv.br Departamento de Solos – UFV e-mail: elpidio@ufv.br José Ricardo Liberato Agronomy Engineer, M.S. - Departamento de Fitopatologia – UFV e-mail: jricardo@alunos.ufv.br

INTRODUTION The QUANT software (Vale et al., 2001) was developed to quantify disease severity from the images obtained by a scanner or digital cameras. QUANT has five image processing procedures: Black and white threshold; Color selection using pallets; Color selection by coordinate interval of the color system; Color selection by sampling; Color selection by discriminants functions. The last procedure permits complete automation of the process. The dozens or hundreds of thousands of colors of the original digital image are reduced to only three or four, each one representing, for example, the image's background, and healthy, chlorotic and necrotic tissues. QUANT provides the leaf area of healthy and disease (chlorotic, necrotic, and sporulated) tissues, the disease severity, as well as the number, size, form and position of lesions on the leaf. The five procedures are, step by step, described and illustrated as follows. For this, a scanned, 300 dpi digital image (file Figure 1.bmp) of maize-Phaeosphaeria maydis pathosystem will be used.

1.Obtaining the image through scanner I. Obtaining the Digital Images 1.Obtaining the image through scanner Initially this program is being evaluated using images obtained through scanner, at 300 dpi, in the windows bitmap format (bmp). Obs.: QUANT itself can obtain the scanner image, as shown below:

     2. Obtaining the digital camera image 2.1 Image calibration When using the digital camera for obtaining the images, it is important to have in the image an object (for example, a ruler) of the known size, so that the calibration of its size can be done by the QUANT.

Resolution (incorrect) of the image: In the absence of information, QUANT initially considers this resolution that needs to be corrected

Ruler (cm)

Click on the left button of the mouse and drag

2. Inform the real lenght of the line 1.To make a straight line

Resolution of image

Calibration of the scanner obtained image Images obtained through scanner are automatically calibrated by QUANT, on opening the file. However, while working with a section of this image, the program does not recognize the correct resolution of the image. Therefore it is necessary to calibrate it. Obs.: An example of working with a section of a 300 dpi scanner image is given below:

Incorrect resolution of image

Incorrect resolution of image

Digit the original resolution

Correct resolution of the image

How to use the zoom

Zoom Size: % of the original image

2. Or change the zoom value 1a. Turn-on the zoom button 1b. Click on the left button of mouse to increase the size of the image

Or chage the zoom value Click on the right button of the mouse to decrease the size of the image

Determining the number of colors of the image

Coordinates RGB: a picture can have up to 2563 colors

The final objective of the QUANT

61253 colors 3 colors The final objective of the QUANT is to reduce the number of colors and quantify the areas occupied by each of them

Procedure for color processing Selection of colors: - using pallet (tutorial 2); - by sampling (tutorial 3); - by coordinate interval of the color system (tutorial 4); - by discriminant functions (tutorial 5); - black and white threshold (tutorial 6); - Measuring the individual lesions (tutorial 7); - Images with little contrast between lesioned and healthy area (tutorial 8)