hair volume/surface measurement – fly-away/frizz analysis system

Bossa Nova Technologies www.bossanovatech.com 11922 Jefferson Blvd. [email protected] Culver City, CA 90230 Tel: (310) 577-8113 USA Fax: (310) 943-3280

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Hair volume/surface measurement – fly-away/frizz analysis system

Technical Note - July 2016

1 – Introduction

BOLERO is a turnkey imaging system dedicated to hair swatch 3D volume reconstruction and fly-away/frizz

analysis. Based on the acquisition of a sequence of contour images of a swatch, the BOLERO delivers a 3D

model of the hair swatch. The system also simultaneously provides volume and surface measurements as

part of the 3D model, including frizz/fly-away analysis. Application of the BOLERO ranges from claim

substantiation and product efficacy testing for volumizing products, to basic analysis of hair swatch

volume and visual appearance.

2 – Bolero

Figure 1 shows BOLERO.

Figure 1: BOLERO with door open showing the hair tress and the LED background

BOLERO is composed of a digital camera, an LED illumination background for back light illumination and a

hair swatch mount placed on a rotation stage. To achieve an accurate measurement, the hair swatch must

be isolated from any air displacing variables (A/C or other sources) which may distort shape and therefore

3D volume reconstruction. To this end, the swatch is clipped to a holder (Figure 2), and the whole system

is incased in an enclosure. A magnetic door allows the user to easily close the enclosure and open it when

the hair swatch needs to be changed.

http://www.bossanovatech.com/

mailto:[email protected]


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Figure 2: Hair swatch holder

As the hair swatch is rotated, images are acquired at various angular intervals. Once all images have been

acquired, processing software extracts the contour of each image, constructs a 3D model of the hair

swatch and provides analysis of the fly-away/frizz. BOLERO is connected to a computer for data/image

acquisition, processing and data visualization/analysis/management (Figure 3). 2 USB connectors are used

to connect the rotation stage (USB 2.0, white) and the camera (USB 3.0, blue) to the computer. A power

supply and an on/off button allows to power on/off the whole system.

Figure 3: Picture of connections

3 – Software

The software performs data management, data acquisition/processing, data visualization and data export.

At startup, the user can choose between live measurement & load data or load data only if no hardware

is connected or no measurement is scheduled (Figure 4).




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Figure 4: Start-up window

Choosing live acquisition leads to an automated test procedure that insures all hardware components

(camera, rotation and LED panel) are working properly to the factory specifications (Figure 5). In case of a

problem with the hardware, various error message will appear. If the system is not turned on, the user

will only be able to upload, visualize and analyze former data.

Figure 5: Hardware self-test and calibration

Figure 6 shows the DATA MANAGEMENT window (Live measurement is on as Add new measurement

button is present).




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Figure 6: Main window – DATA MANAGEMENT

The main window - named data management - allows the user to create or delete studies (and their

contents), create or delete sub-folders (and their content) and delete measurement, for easy data

management. A preview of the first image of a selected measurement is displayed.

The main window also allows the user to load measurement(s) to the data analysis window, for both

visualization and comparison. This is achieved clicking on the “LOAD Measurement to DATA Analysis”

button or by adding a new measurement to the data library using the “Add new measurement” button.

The main window allows the user to add a new measurement if live measurement and load data was

selected, or reprocess an existing measurement, by selecting the reprocess measurement button.

The exit button will close the software.

Figure 7 shows the data analysis window.




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Figure 7: Data analysis window

On the left of the window, the Loaded or Uploaded MEASUREMENTS box lists all loaded data. The easy to

use, large blue arrow shifts measurements from the Loaded MEASUREMENTS list to the MEASUREMENTS

Displayed list, for up to 9 measurements. Data from MEASUREMENTS Displayed will appear in both visual

and list format.

Figure 8: Displayed measurements




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The RESULTS TABLE lists the volume (in mm3), surface (in mm2) and frizz/fly-away percentage (%) for each

measurement (Figure 9).

Figure 9: Results table

It is possible to select a measurement as a reference by clicking the “SELECT measurement as REFERENCE”

button, the user can then update the RESULTS table in order to easily compare different measurements

relative to the selected reference (Figure 10).

Figure 10: Results table with REFERENCE measurement (Blond 3 is the reference)

The user can display the images by using the 7 tabs at the top of the visual rendering window (Figure 11).

Figure 11: Images

By selecting the image viewed (raw or FAF), the user can change the visualized images (Figure 12).




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Figure 12: Images visualized

The Area versus z tab allows the user to visualize the variation of the area of the swatch versus z.




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Figure 13: Area versus the z axis

The Perimeter versus z tab allows the user to visualize the variation of the perimeter of the swatch versus

z.

Figure 14: Perimeter versus the z axis

The Fly-away/frizz versus z tab allows the user to visualize the variation of the Fly-away/frizz of the swatch

versus z.




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Figure 14: Fly-away/Frizz versus the z axis

The 3D plot tab allows the user to visualize the selected loaded 3D shape. The user can rotate the 3D

shape as needed and export the image as a jpeg file.

Figure 15: 3d shape

The slice tab allows the user to visualize the slice of the loaded measurements and navigate through z. A

calculation of the area and the perimeter of the slice(s) is given.




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Figure 16: Slice

Displayed data can be exported using the “EXPORT Results” button. A pop-up windows appears, asking

the user to create a new folder where various images and data will be saved.

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Figure 17: Exporting results




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To add a new measurement, the user clicks on the Add new measurement button located near the

measurements list on the upper right of the data management window.

Figure 18: Add new measurement button

Figure 19 shows the measurement window after clicking the “Add new measurement” button in the data

management window.

Figure 19: Measurement window – Swatch limit automatic

If swatch limit automatic is selected, the software will determine the swatch limit automatically by

processing. The swatch start (in blue) remains adjustable in order to remove the undesirable swatch

holder features (rubber band, etc.). If the user wants to adjust the swatch limit manually, a click on the

swatch limit automatic button make the swatch limit control appears (in red). The user can then adjust

the swatch limit as desired.




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Figure 20: Measurement window with swatch limit manually adjustable

Once the swatch limit and start are adjusted, in order to crop the top and bottom of the image (blue and

red lines) the user simply clicks the “START” button and a pop-up window will then appear asking for a

measurement name (Figure 21).

Figure 21: measurement name pop-up windows

Clicking on save will also start the measurement process with the acquisition of the images during the hair

swatch rotation.




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Figure 22: Measurement in progress

A count down of the time remaining until completion is then displayed along with the percentage of

completion. Once the measurement is complete, processing begins.

Figure 23: Processing in progress

Similarly, a countdown of the processing time remaining is displayed along with the percentage of

completion. Once processing is complete, the volume, surface and frizz/fly-away percentage is displayed

along with the 3D model of the hair swatch (Figure 24). The tab allows to visualize the area, perimeter or

Fly-away/Frizz percentage versus z.




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Figure 24: Measurement done – Results window (Area versus z selected)

Data automatically saved to the measurement folder are raw images, a FAF image, the XYZ point cloud

text file and the (area, perimeter and FAF versus z) text file. Do not modify or move any of the files in this

folder as it will result in software problem.

The “Exit meas.” Button closes display windows in order to return to the data measurement window.

The user has also the choice of reprocessing existing data. This option is similar to Add a new

measurement as the software will only use the existing raw images and update the other data.




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4 – Example of study

Below is a simple example of a product efficiency evaluation. 6 swatches were used (3 dark, 3 brown) as

presented in Figure 21. Volume and fly-away/frizz percentage are measured.

Figure 25: used 6 swatches (3 dark hair, 3 brown)

A “sleek and shine” styling spray was then applied on each hair swatch followed by volume and fly-

way/frizz % measurement using BOLERO.

Results are presented in the table below:

Hair Swatch # Volume (mm3)

Volume (mm3) Product

Change (%) Fly-away/frizz

(%) Fly-away/frizz (%) Product

Change (%)

200 1.145 105 5.793 104 -49.4 32.30 3.62 -88.8

201 1.231 105 5.415 104 -56 20.18 6.08 -69.9

202 1.302 105 1.08 105 -17 15.74 3.96 --74.8

210 1.07 105 9.208 104 -14 15.54 4.09 -73

211 1.684 105 1.139 105 -32.4 15.74 4.12 -73.8

212 1.379 105 7.37 104 -46.6 13.40 4.26 -68.2

AVERAGE -28.9 -68.2

Using the BOLERO it is possible to conclude that the “sleek and shine” styling spray decreases the

volume of sample hair swatches by 29% and the percentage of fly-away/frizz by 68%.




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Technical Specifications

Camera Monochrome 8 bits

Resolution 2,592 x 1,944 pixels

Illumination Back light LED panel

Hair swatch length From 5cm to 30 cm

Hair swatch color Any

Software BOLERO 3.00 – Windows 10

Measurement Time < 1 minute

Data saved Raw images, FAF image, XYZ point cloud,

area/perimeter/FAF file

Data Export Excel format

Calibration Factory calibrated

Size 15” x 30” x 20” (375 mm x 750 mm x 500 mm)

OPTION Internal humidity chamber

AUTOMATICALLY SAVED DATA FORMAT: The data saved have the following format: A folder named Raw

Images where all the images are saved, a png image named bulkfaf.png showing typical bulk and fly-

away/frizz, a text file named APFAF that contains the Area (A), Perimeter (P) and Fly-Away/Frizz (FAF)

versus z and a text file named XYZ that contains the point cloud of the 3d reconstructed hair swatch.

The raw images folder contains the N images acquired during the 360 degree rotation, and the N images

cut between Zmin and Zlimit (automatic or manual) in png format.




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We do not recommend to proceed to any change in these folders and files as it can lead to error in Bolero

software.

EXPORT FORMAT: The exported measurement folder content is shown below. 2 folders respectively

contain images and point clouds, and an Excel file presents the different results and graphs.

The Pictures folder contains one raw image and one fly-away/frizz image for each measurement exported.

The Point Clouds folder contains the point cloud in text file format (.txt) of each measurement exported.




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Finally, an Excel file is generated. It contains the table comparing the volume, area and fly-away/Frizz

(%) of each exported element.

It also contains the various data and graph (Area, Perimeter and Fly-away/Frizz (%) versus z.

For best results, we recommend to use “round” swatches and no “flat” swatches as shown on the picture

below.




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Repeatability Testing

The example below consists of 1 swatch measured 10 times in a row, with no repositioning between

measurements.

Variation: 0.05%




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Repeatability Testing with Repositioning

The example below consists of 1 swatch measured 10 times in a row, with the swatch being repositioned

between measurements.

Variation: 3%




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Technical background

Hair swatches are composed of two differentiable aspects, bulk and frizz/fly-away fibers. The bulk of the

tress can be defined as a 3D closed volume (the mass of hair that comprises the body of the tress), while

frizz and fly-away are individually identifiable fibers. In order to extract a measurement of the bulk, it is

necessary to subtract frizz/fly-away fibers. The system accomplishes this operation using the back light

illumination in conjunction with image processing. If background light transmission through the hair

exceeds 50%, i.e. hair density is less than necessary to block half the light behind the tress, the hair is

considered to be frizz/fly-away. Conversely, if less than 50% of the light passes through a volume of hair,

it is considered part of the bulk. This differentiation criteria is not dependent on color, but is nonetheless

optically relevant (Figure 18).

Following extraction, it is relatively simple to calculate the Frizz/fly-away percentage. Analysis consists in

measuring the ratio of frizz/fly-away to bulk pixels. Using images of the silhouette acquired during




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rotation, it is then easy to reconstruct a 3D model. The model is then used to calculate the hair swatch

surface and volume, employing the technique described in the references below.

References:

“Acquiring 3-D models from sequences of contours”, J. Y. Zheng, IEEE transactions on pattern analysis and

machine intelligence, Vol. 16, N0 2, February 1994

“Area and volume measurements of objects with irregular shapes using multiple silhouettes”, D.J. Lee, X.

Xu, J. Eifert and P. Zhan, Optical Engineering 45 (2) 027202 (February 2016)



hair volume/surface measurement – fly-away/frizz analysis system

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