CS320n –Visual Programming

CS320n –Visual Programming

Image Manipulation

Visual Programming Image Manipulation 2

What We Will Do Today• Look at how to alter images using

LabVIEW


Loading Images VI• Block Diagram of VI that allows user to

load jpg images from a file and displays the image


Image Data• The image cluster contains a

lot of data• The heart of the image is an

array of ints– each int only uses 1 byte or 8

bits– represents a number from 0 –

255

• three ints in a row represent the red, green, and blue intensity for 1 pixel– elements 0, 1, 2 are for the pixel

at row 0, column 0, the upper left corner


Image Data


RGB Colors• What color is that pixel at the top left

corner? Looks very black

• Unbundle image to get at image array


RGB Colors• First three elements of

image array are 27, 26, and 5

• Intensity of red from 0 to 255– 0 is none, 255 is maximum

• a little red, a little green, almost no blue

• very close to black, all three 0


Viewing a Single Color• Developed a VI to do this in an early lab

• a single function exists

Controls and indicatoradded.


Sample Single Colors

Moss? Black.


How Many Colors• If the encoding of an image allows red,

green, and intensity values of 0 – 255 there are

• 256 * 256 * 256 = 16,777,216 possible colors

• 1 byte per color per pixel

• 3 bytes total per pixel, 24 bits

• a.k.a. 24 bit image


Altering Images• Some programming tools allow individual pixels

or areas to be affected, recolored.• We will look at altering image by affecting all

pixels in the image• need to work with the color data• can work with the array of colors from image• OR “unflatten” the image data to a 2d array

– go from an array of 1 dimension (like a list) to an array with 2 dimensions, like a table


Unflatten Image Function• Most interested in the 24-bit pixmap


Unflattening the ImageImage Wire

Displaying value in element 0,0Shown as a hexadecimal number,base 16.1B = red component, 1 * 16 + 11 * 1 = 271A = green component, 1 * 16 + 10 * 1 = 2605 = blue component, 0 * 16 + 5 * 1 = 5


One filter – Invert image• Invert the image

– set each pixel = 16,777,215 – original value

• auto indexing really shines

2d array1d array single element

flatten back to image


Original


Result

CS320n –Visual Programming

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