Posts by CarmenZ

    Dear Baoxi,

    please find attached a ViausalApplets design example, for the definition of a round central region. The idea of the design is to go in a coordinate system reletive to the image center, and calculate the distance of the current position relative to the center of the image. Then we can set all pixels outside a specific radius to value zero.



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    Dear Baoxi,

    thank you for your answer. As the region of interest is a circle I have some additional questions:

    1. Do you know the coordinates x and y, where there is useful or useless information without further image processing?

    2. Is it suitable for you to do a filtering by setting the useless pixel to zero value?

    If yes, you can think of a processing like sketched in the following:


    With this processing you can set all pixels outside a specified region to a zero value. You also can combine this processing with a previous selection of a rectangular region of interest for example using operators SelectROI, DynamicROI,....

    Dear Danna,

    thank you for your question.

    Please find under "...\Examples\Processing\Color\bayer" in your VisualApplets installation directory multiple examples for Bayer demosaicing. Under…ent/bayer%20Overview.html you can find a detailed description for these examples.

    Under "...\Examples\Processing\..." in you VisualApplets installation directory there are more image processing examples which might be of interest for you: E.g. examples for image composition ("..\Examples\Processing\HDR_ImageComposition") . Under "..Examples\Acquisition\BasicAcquisition\..." you can find examples for basic image acquisition designs.

    Dear Sangrae Kim,

    under "\examples\Processing\Geometry\GeometricTransformation\" in your VisualApplets installation directory you can find an example for distortion correction implementation. This example is based on the OpenCV implementation for the determination for the correction coefficients. Please find a detailed description on this example under…l#Distortion%20Correction.

    Dear Saito-san,

    thank you for the question. You may use a "LineMemory" operator as it is used in the VisualApplets example "" under "Examples\Processing\Geometry\TapGeometrySorting" in the VisualApplets installation directory.

    Dear Saito-san,

    thank you for your question.

    I had a look on the description of Halcon function "fit_surface_first_order" (…_surface_first_order.html ) : This function approximates a first order surface plane to a gray value object in minimizing the distance between gray values and plane. Also the gray value moments are calculated.

    I think such functionality can be implemented in VisualApplets using loop functionality and a geoemetric scaling function within this loop to approximate a plane to an object.

    Under (…n/moments_gray_plane.html.) I found a similar Halcon function : "moments_gray_plane". It also calculates the gray value image moments and approximates a plane. Only method for plane claculation is different. As it seems from description it maybe possible to implement in Visual Applets without loop functionality. Is this method also of interest for the customer?

    Dear JSuriya,

    thank you for your request.

    Do you refer to the Visual Applets example ""?

    Please may you explain "reference points"? Do you mean rotation, translation and scaling with respect to a certain point (E.g center of gravity)?

    Of cource instead of rotation around center of gravity you can choose any other point in the image to perform the transformation.

    Dear Saito-san,

    thank you for your request.

    Maybe a combination of following operators is of interest for you:

    1. Signal Edge(Rising Edge):A pulse of one clock cycle is generated, when a rising edge of the input signal is detected

    2. SignalToWidth:The operators measures the pulse width of the signal at the input (=1 in this case). The result is output as a 0D pixel value at output link.

    3. Multiplication by a user defined factor, which is the period of the output signal

    4. PeriodToSignal:The operator generates a periodic signal at its output. The period time is controlled by the pixel value at the input link I. Thus the operator converts the input stream values into a signal with the period provided by the pixel values. The high time of the output pulses is one tick.

    Dear Danna,

    thank you for your questions.

    1. Concerning you question from Februray 23rd:

    Please find attached the design "" : In this design an example for the calculation with so called fractional bits is implemented:

    For the calculation in VisualApplets you can only use Integer values. When you want to perform division or other mathemetical operations with values smaller than 1 you can use a "trick":

    For example input pixel value I=2:

    -Division by 20: 2/20= 0.1

    -Problem: Only integer values can be processed

    -Solution: Mulitply input by 2^x: x e.g. =10: We call this fractional bits

    -2*(2^10)/20= 102,4 => Value 102 (with 10 fractional bits) is result from division operation

    -102 corresponds to 102/2^10, which is ~0.1

    The more fractional bits you use the more accurate the result from division operation is.

    2. Concerning your request from March 3rd:Build problems of hap file:

    The design clock is set to 312 Mhz in design "". This is causing the timing error.

    Please reduce the design clock frequency to 125 MHz.



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    Dear JSuriya,

    "..You can connect the images from different processes using operators "RxImageLink" and "TxImageLink".-..."

    I apologize: this information is not correct. You can only exchange signals between the independent processes via "RxSignalLink/Tx signal link" not the image data.

    (see"Interprocess communication" under…multiple%20processes.html)

    In the attachment you find the design"" for the stitching of the images for the three cameras. Please test it.

    Dear JSuriya,

    thank you for your request.

    "..But I need all the cameras to be in a same process so that I can append the images from the cameras for further processing ..."

    You can connect the images from different processes using operators "RxImageLink" and "TxImageLink".

    Concerning the problem with the image acquisition when more than camera is contained in one process:

    Maybe the reason for your problem is described under…ultiple%20processes.html:

    The cameras in the same process have to be started and stopped simultaneously, as all DMAs of a process have always to be started.

    The processes are indenpendent and can be started and stopped individually.

    Dear Matthias R,

    thank you for your question. May you send a snippet of your VisualApplets design for the problemtic situations , so we can sketch a possible solution?

    The modification of parallelism and number of kernel components could help in such situations.

    The Image size of Coefficient Buffer is limited due to DRAM size. This may be a reason for the problems you observe. The operator Create Blank image does not have this restriction.

    Dear Danna,

    thank you for your request.

    Please find attached a VisualApplets design in which following processing is implemented:

    Input a gray: pixel I (I, J),

    If I(I,J)<64,: r = 0, g = 4 * I (I, J), B = 255;

    If 63 < I(I,J)< 128: r = 0, g = 255, B = 255-4 * [I (I, J) - 64]

    If 127< I(I,J)<192: r = 4 * [I (I, J) - 128], G= 255, B = 0

    If 191< I(I,J): r = 255, g = 255-4 * [I (I, J) - 192], B = 0

    The only difference to the color processing you have described is for the case 63 < I(I,J)< 128. In order to be sure to have 8 bit value (less than 255), the value 128 was substituted by 64.

    I hope this design is helpful for you.



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    Dear Janek,

    thank you for your request.

    You can use the Visual Applets example "" for upscaling the image in both image directions by a factor of 1.17. This example is DRAm based,but maybe can solve your problem:

    Right-Mouse-click on the module "GeometricTransformation" and set under properties following parameters:


    Dear Jayasuriya,

    thank you for your question. We use this procedure because only interger values are allowed for the parameters in VisualApplets.

    The reference angle chi and alpha is multiplied by a factor 1024/90, to covert degree to fixed point parameter value

    I.E. 90°= 1024, and 27,77°= 316

    Also the multiplication by a factor of 2^2=4 of the distance is due to the fixed point t arithmetic and correspond to the subpixel accuracy.

    This means: 2^2 correspond to distance of 1. If you like to set a distance Z of 0.5 we use value of 2 in VisualApplets.

    Dear Sangae Kim,

    thank you for your request.

    You can use the Visual Applets example "" for upscaling the image in both image directions by a factor of 2.

    Right-Mouse-click on the module "GeometricTransformation" and set under properties following parameters


    Dear Jayasuriya,

    thank you for your question:


    I am having doubts in applet). How to find center of gravity of object,angle alpha,angle chi and distance Z...."

    Please find attached a sketch of the patterns A and B ( part of object) and the Center of gravity (COG) of object.

    If you want to rotate not around the center of gravity you can chhoose any other point to rotate around. You can select any pattern on the objects. I recommend to select patterns which appear only one time in the object and are mostly rotation invariant.

    In the image in the attachment also the angles alpha, chi and the distance Z between pattern A and the COG are sketched.

    Calculation of angle alpha:

    with x_A, y_A : x and y coordinate of pattern A,

    x_B, y_B : x and y coordinate of pattern B,

    x_COG, y_COG: y coordinate of COG

    alpha= arctan((y_A - y_COG)/(x_COG-x_A))-chi)

    calculation of angle chi

    chi=arctan((y_A - y_B)/(x_B-x_A))

    calculation of distance Z:


    Please see also under…%20Inspection%20Blob.html a detailed documentation on the design ""

    Also the design "" maybe of interest for you:

    In this design the rotation angle and position shift calculation of an object is not pattern based but it is based on the calculation of image moments

    (see e.g.

    Concerning your question


    In ''split fraction and integer bit'' hierarchical box which conversion is used to convert 959 into 15712255 (input to 'is in range' operator)..."

    In the hierarchical box "LimitCoordinateValues" in module "SplitFractional And IntegerBit" the coordinates are limited to the maximum input image coordinates. Due to the geometric transformation performed in module "InverseTrabnsformation" in module "geometricTransformation" 14 fractional bits remain.

    This means coordinate of 959 corresponds to 959*2^14=15712255.

    I hope to help you with these explanations.

    Best regards

    Carmen Z