Changes between Version 76 and Version 77 of UvmatHelp


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Timestamp:
Jun 27, 2013, 11:12:23 PM (7 years ago)
Author:
sommeria
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  • UvmatHelp

    v76 v77  
    221221
    222222=== 4.1  Images and scalars: ===
    223 Images are matrices of integers, visualised by the Matlab function ''imagesc.m''.
     223Images are matrices of integers, visualised by the Matlab function ''imagesc.m''. The number of pixels in x and y is indicated in the boxes '''[num_Npx]''' and '''[num_Npy]''' respectively. Note that while the x coordinate of the image ranges from 1/2 to npx-1/2, the pixel index in y ranges from the maximum ordinate npy-1/2 to the smallest one 1/2.
    224224
    225225True color images are described by a matrix A(npy,npx,3) of integers between 0 and 255, the last index labeling the color component red, green or blue. They are displayed directly as color images.
     
    227227[[Image(help_scalar_titres.jpg)]]
    228228
    229 The greyscale images are described by a matrix A(npy,npx) of integers, whose range depends on the camera dynamics (0 to 255 for 8 bit images, 0 to 65535 for 16 bit images). They are represented with gray levels, according to the colorbar displayed on the right. The luminosity and contrast can be adjusted using the edit boxes '''[num_MinA]''' and '''[num_MaxA]''' on the right of the interface: the luminosity level set by '''[num_MinA]''' (and levels below) is represented as black, and the luminosity level set by '''[num_MaxA]''' (or levels above) as white. When the check box '''[!CheckFixScalar]''' is not selected, these bounds are set automatically to the image minimum and maximum respectively. Then the image may appear dark if a single point is very bright, in that case a lower value must be set by '''[num_MaxA]'''. Greyscale images can be displayed with false colors, from blue to red, by unselecting the check box '''[CheckBW]'''.
     229The greyscale images are described by a matrix A(npy,npx) of positive integers. The luminosity range depends on the camera dynamics (0 to 255 for 8 bit images, 0 to 65535 for 16 bit images). Luminosity represented with grey levels, according to the colorbar displayed on the right. The luminosity and contrast can be adjusted using the edit boxes '''[num_MinA]''' and '''[num_MaxA]''' : the luminosity level set by '''[num_MinA]''' (and levels below) is represented as black, and the luminosity level set by '''[num_MaxA]''' (or levels above) as white. When the check box '''[!CheckFixScalar]''' is not selected, these bounds are set automatically to the image minimum and maximum respectively. Then the image may appear dark if a single point is very bright, in that case a lower value must be set by '''[num_MaxA]'''. Greyscale images can be displayed with false colors, from blue to red, by unselecting the check box '''[CheckBW]'''.
    230230
    231231Note that greyscale images with low resolution are linearly interpolated on a finer mesh for nicer display. This interpolation can be also done as image processing by defining a grid on a projection object 'plane', see [#ProjObject section 6].
     
    252252-'''Associated scalar: '''  for PIV velocity fields, the color  represents by default the image correlation '''C''', ranging from 0 to 1.  The red values correspond to poor correlations, green to fair values, and blue to good ones. The value range covered by each of the three colors is set by the pair of sliders  '''[Slider1]''' and '''[Slider2]''', or equivalently by the edit boxes '''[num_ColCode1]''' and '''[num_ColCode2]'''. Other color representations can be specified. '''[!ColorScalar]''' sets the scalar used for color representation, for instance the vector norm 'norm_vec' or vorticity 'vort' (the list of available scalars is set by the function {calc_scal.m}).
    253253
    254 -'''[ColorCode] ''' sets the kind of color representation:
    255  * 'rgb':  color ranging from red, for the scalar value set by '''[num_MinVec]''', to blue, for the scalar value set by  '''[num_MaxVec]'''. The  color thresholds from red to green and green to blue are set by '''[ColCode1]''' and '''[ColCode2]''' respectively, or the sliders  '''[Slider1]''' and '''[Slider2]'''. By unselecting the check box [CheckFixVecColor], these thresholds can be set to match the min and max scalar values.
     254-'''[!ColorCode] ''' sets the kind of color representation:
     255 * 'rgb':  color ranging from red, for the scalar value set by '''[num_MinVec]''', to blue, for the scalar value set by  '''[num_MaxVec]'''. The  color thresholds from red to green and green to blue are set by '''[ColCode1]''' and '''[ColCode2]''' respectively, or the sliders  '''[Slider1]''' and '''[Slider2]'''. By unselecting the check box [!CheckFixVecColor], these thresholds can be set to match the min and max scalar values.
    256256 * 'black' or 'white': set the color for all vectors
    257257 * 'brg': same as rgb but in reverse order, with blue for the lowest scalar values.