1. A method for detecting free fibre ends in a paper surface, the method comprising
illuminating a target sample surface, which comprises free fibre ends, from at least two directions one direction at a time, with at least one light source,
obtaining for each light source direction an original reflectance image for the target sample surface with an imaging device,
estimating a surface normal for each image pixel of the original reflectance image,
reconstructing a reconstructed reflectance image from the estimated surface normals, and
comparing the reconstructed reflectance image and the corresponding original reflectance image and constructing a difference image, where the differences represent shadow objects of the free fibre ends in a paper surface.
2. The method according to claim 1, characterised in reconstructing a plurality of reconstructed reflectance images from the estimated surface normals,
comparing each reconstructed reflectance image and the corresponding original reflectance image and constructing difference images, where the differences represent shadow objects of the free fibre ends in a paper surface, and
calculating an average value of the number of the shadow objects in the difference images.
3. The method according to claim 1, characterised in that the unit normal of the surface for each image pixel is estimated by minimizing the square of error with pseudoinverse as
n
=
(
L
T
\ue89e
L
)
–
1
\ue89e
L
T
\ue89e
i
\u03c1
\ue89e
\ue89e
E
where n is the unit normal of the surface, p is the surface albedo describing the reflectivity of the surface, E is the intensity of a light source, L is the matrix consisting of 1\xd73 unit vectors towarding each light source, and i is the intensity vector of the image pixel for each light source direction.
4. The method according to claim 3, characterised in that the reconstructed reflectance image is reconstructed by calculating the reflectance intensity for each image pixel from the equation
i=\u03c1EL1\xd73n3\xd71,
5. The method according to claim 1, characterised in compensating the beam pattern of the light source on the target sample surface by using a 2D second order polynomial fitted on the original reflectance image.
6. The method according to claim 1, characterised in
compensating pixel intensity values by computing the distances between the each image pixel and the light source in order to obtain a matrix of pixel intensity compensation results, and
multiplying the original reflectance image pointwise with the matrix of pixel intensity compensation results and dividing the original reflectance image pointwise with a 2D polynomial.
7. The method according to claim 1, characterised in detecting the shadow objects in the difference image by using filtering andor processing methods which enforce the shadow objects of the free fibre ends in a paper surface.
8. The method according to claim 7, characterised in
computing a histogram which shows the distribution of pixel values of the filteredprocessed difference image in which the shadow objects are enforced,
setting a threshold limit to a desired value and obtaining a thresholded difference image,
removing circular objects from the thresholded difference image by using ellipse fitting algorithms, and
accepting from the thresholded difference image shadow objects whose length is larger than an acceptance limit, andor objects having eccentricity exceeding a predetermined value, andor objects which major axis deviates at the most 30 degrees, 45 degrees or 90 degrees from the direction of the light source.
9. The method according to claim 1, characterised in illuminating the target sample surface, which comprises free fibre ends, from at least 6, preferably at least 8, more preferably at least 10, even more preferably at least 12, directions.
10. The method according to claim 1, characterised in that the target sample is moving paper web and that the method is performed on-line.
11. The method according to claim 1, characterised in counting the number of shadow objects and changing process parameters according to the obtained result.
12. The method according to claim 1, characterised in
arranging a first linear polarizer in front of the imaging device and a second linear polarizer in front of the light source, the first and the second linear polarizer being at 90 degrees angle in relation to each other, and
keeping the orientation between the polarizers constant during the measurement.
13. An arrangement for detecting free fibre ends in paper, especially in tissue paper grades, the arrangement comprising
an imaging device such as a digital systems camera, arranged to a distance from the sample holder, for obtaining original reflectance images of a target sample surface,
at least two light sources, such as LED, attached around the imaging device, or one light source, which is attached to a supporting arm, which is arranged to rotate around the imaging device, the at least two light sources or the one light source being arranged to illuminate the target sample surface from at least two directions one direction at a time,
a data processing unit, which is arranged
to receive original reflectance images obtained for each light source direction from the imaging device,
to estimate a surface normal for each image pixel of the original reflectance image,
to reconstruct a reconstructed reflectance image from the estimated surface normals, and
to compare the reconstructed reflectance image and the corresponding original reflectance image and to construct a difference image, where the differences represent shadow objects of the free fibre ends in a paper surface.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
I claim:
1. An article of furniture in the form of a combination cabinet and folding bed comprising:
a cabinet having a front opening, spaced-apart vertical side walls, a top wall, a back wall and a front molding;
a front panel having a first end hingedly attached to said front molding such that said front panel is capable of rotation about an axis of rotation between a substantially vertical position wherein said front opening is covered and a substantially horizontal position;
one or more attachment strips removably secured to an inside surface of said front panel;
an articulate mattress assembly having a head frame, a foot frame and a hinge member, said head member having one or more brackets removably secured to said attachment strips, said hinge member rotatably secured at a first end to said head frame and rotatably secured to said foot frame at a second end such that said mattress assembly may be stored within said cabinet, said head frame, said foot frame and said hinge member capable of being folded upon each other in spaced relation to receive a mattress;
a middle support member rotatably secured to said hinge member for engaging the floor; and,
a foot support member rotatably secured to said foot frame for engaging the floor.
2. The article of claim 1, wherein said middle support member further comprises rubberized feet for minimizing slippage of said middle support member upon engaging the floor.
3. The article of claim 1, wherein said foot support member further comprises rubberized feet for minimizing slippage of said foot support member upon engaging the floor.
4. The article of claim 1, wherein said middle support member is attached to said hinge member using a slot and pin arrangement.
5. The article of claim 1, wherein said front panel is composed of plywood and further comprises an outside surface having pull knobs for facilitating movement of said front panel from a substantially vertical position to a substantially horizontal position.
6. The article of claim 1, wherein said head frame further comprises at least one retaining clip for releaseably engaging said foot frame.
7. The article of claim 1, wherein said foot frame further comprises a velcro strap capable of securing said foot support member to said mattress assembly.
8. The article of claim 1, wherein said inside surface of said front panel further comprises one or more assembly mounts for engaging said mattress assembly.
9. The article of claim 1, wherein said hinge member further comprises a handle member for providing additional rigidity to said hinge member and for grasping by the user.
10. The article of claim 1, wherein said attachment strips are mounted in a plane parallel to said axis of rotation of said front panel and span substantially the entire width of the inside surface of said front panel.
11. The article of claim 1, wherein said head frame, said foot frame and said hinge member further comprise cross members for providing additional stability and support.
12. The article of claim 1, wherein said mattress is between about 3 to about 4 in thickness.
13. A method of using an article of furniture having the form of a combination cabinet and folding bed comprising the following steps:
providing a cabinet having a front opening, spaced-apart vertical side walls, a top wall, a
back wall and a front molding;
a front panel having a first end thereof hingedly attached to said front molding such that said front panel is capable of rotation about an axis of rotation between a substantially vertical position wherein said front opening is covered and a substantially horizontal position;
one or more attachment strips removably secured to an inside surface of said front panel;
an articulate mattress assembly having a head frame, a foot frame and a hinge member, said head member having one or more brackets removably secured to said attachment strips, said hinge member rotatably secured at a first end to said head frame and rotatably secured to said foot frame at a second end such that said mattress assembly may be stored within said cabinet, said head frame, said foot frame and said hinge member capable of being folded upon each other in spaced relation to receive a mattress;
a middle support member rotatably secured to said hinged member for engaging the floor; and,
a foot support member rotatably secured to said foot frame for engaging the floor;
moving said front panel from a substantially vertical position to a substantially horizontal position;
rotating said middle support member from a stored and locked position to an open position;
locking said middle support member into an open position;
unsnapping said foot frame from at least one retaining clip attached to said head frame and
pivoting said foot frame from a collapsed position to an open position such that said foot support member is simultaneously rotated from a closed position to an open position.
14. A method of storing an article of furniture having the form of a combination cabinet and folding bed comprising the following steps:
providing a cabinet having a front opening, spaced-apart vertical side walls, a top wall, a back wall and a front molding;
a front panel having a first end thereof hingedly attached to said front molding such that said front panel is capable of rotation about an axis of rotation between a substantially vertical position wherein said front opening is covered and a substantially horizontal position;
one or more attachment strips removably secured to an inside surface of said front panel;
an articulate mattress assembly having a head frame, a foot frame and a hinge member, said head member having one or more brackets removably secured to said attachment strips, said hinge member rotatably secured at a first end to said head frame and rotatably secured to said foot frame at a second end such that said mattress assembly may be stored within said cabinet, said head frame, said foot frame and said hinge member capable of being folded upon each other in spaced relation to receive a mattress;
a middle support member rotatably secured to said hinged member for engaging the floor; and,
a foot support member rotatably secured to said foot frame for engaging the floor; pivoting said foot frame from an open position to a collapsed position such that said foot support member is simultaneously rotated from an open position to a closed position;
snapping said foot frame into at least one retaining clip attached to said head frame such that said foot frame is secured in a collapsed position;
unlocking said middle support member into an open position;
rotating said middle support member from an open position to a closed position; and
moving said front panel from a substantially horizontal position to a substantially vertical position.
15. An article of furniture in the form of a combination cabinet and folding bed comprising:
a cabinet having a front opening, spaced-apart vertical side walls, a top wall, a back wall and a front molding;
a front panel having a first end hingedly attached to said front molding such that said front panel is capable of rotation about an axis of rotation between a substantially vertical position wherein said front opening is covered and a substantially horizontal position, said front panel composed of plywood having an outside surface having pull knobs for facilitating movement of said front panel;
one or more attachment strips removably secured to an inside surface of said front panel, said attachment strips mounted to said front panel in a plane parallel to said axis of rotation of said front panel and spanning substantially the entire width of said inside surface of said front panel;
an articulate mattress assembly having a head frame, a foot frame and a hinge member, said head member having one or more brackets removably secured to said attachment strips, said hinge member rotatably secured at a first end to said head frame and rotatably secured to said foot frame at a second end such that said mattress assembly may be stored within said cabinet, said head frame, said foot frame and said hinge member capable of being folded upon each other in spaced relation to receive a mattress;
a middle support member rotatably secured to said hinge member for engaging the floor, said middle support member having rubberized feet for minimizing slippage of said middle support member upon engaging the floor, said middle support member attached to said mattress assembly using a slot and pin arrangement;
a foot support member rotatably secured to said foot frame for engaging the floor, said foot support member having rubberized feet for minimizing slippage of said foot support member upon engaging the floor;
said foot frame comprising a velcro strap capable of securing said foot support member to said mattress assembly;
said inside surface of said front panel comprising one or more assembly mounts for engaging said mattress assembly; and,
said hinge member having a handle member for increased rigidity of said hinge member and for grasping by the user.