Commit a20f421f by Christian Tischer

### EMBL Course

parent 229cd4fb
 ... ... @@ -33,6 +33,13 @@ True or false? - Pixel indices are always positive integer values. - The lowest pixel index of a 2D image always is `[1,1]`.       ## Image display ### Motivation It sometimes is necessary to change numberic content of images. It is important to understand how to do this properly in order to avoid uncontrolled artifacts. It sometimes is necessary to change the numeric content of images. It is important to understand how to do this properly in order to avoid uncontrolled artifacts. What are good reasons to change the pixel values in an image? ... ... @@ -107,20 +115,20 @@ What are good reasons to change the pixel values in an image? * upper left corner at `[ 20, 35 ]` * width = 10 * height = 10 * Subtract the measured background intensity from each pixel * Measure pixel values again at above coordinates ( `[ 28, 35 ]` and `[ 28, 39 ]` ) * Discuss how the pixel values changed during background subtraction * Subtract the measured background intensity from each pixel. * Measure pixel values again. * Observe that the resuls are incorrect. Repeat above activity, but: * After opening the image, convert its pixel data type to floating point * After opening the image, convert its data type to floating point. ### Activity: Limitations of float - Create an empty image - Set all pixel values to 1000000000.0 - Add 1.0 to all pixel values - Be shocked :-) - Be shocked... ...it turns out that from 16777216 on you cannot represent all integers anymore within a float. ... ... @@ -138,6 +146,12 @@ True or false? - [Limitations of float](https://randomascii.wordpress.com/2012/02/13/dont-store-that-in-a-float/)       ## Pixel data type conversions       ## Thresholding ... ... @@ -208,12 +235,12 @@ In order to find objects in a image, the first step often is to determine whethe '/> ## Activity: Threshold an image ### Activity: Threshold an image - Open image: `xy_8bit__two_cells.tif` - Convert the image to a binary image by means of thresholding. ## Formative assessment ### Formative assessment True or false? Discuss with your neighbor! ... ... @@ -222,6 +249,13 @@ True or false? Discuss with your neighbor! - A binary image can have three values: -1,0,+1 - Values below the threshold are always set to 1.       ## Connected components analysis
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!