how greyscale image can convert into binary image?

[sagar1511]

i have 8 bit grey scale image.how i can get binary image?

[James.M]

If you have NI Vision, you do this.

Without NI Vision, you can convert the image to a 2D array and perform a threshold on the array.

[sagar1511]

in imaq threshold what is range and replace value mean?

[James.M]

Well how do you expect to convert to a binary image? What dictates black? What dictates white? So you want black, or do you want some grayish color? You need to set parameters that convert an image that has too much information down to an image with very basic information.

Read the help file.

[sagar1511]

i mean to say that suppose i have 8 bit greyscale image than in what we generally do is set some value suppose it is 150.so above 150 all pixel will white and below it will be black.so it will convert in binary image.is that possible here?

[James.M]

Yes

[sagar1511]

ok..now i  want to do thresholding with value 150 on a 8 bit grey scale value so here what is the range and replace value?

[James.M]

From the help file:

Range is a cluster specifying the threshold range. Lower value is the lowest pixel value used during a threshold. The default is 128. Upper value is the highest pixel value used during a threshold. The default is 255.

Replace Value is the value used to replace pixels between the Lower value and Upper value. This operation requires that Keep/Replace Value (Replace) is TRUE.

So what do you think you should use for the range and replace values?

[sagar1511]

i know this already.but cant understand the replace value and range phenomena.in thresholding why there is a range?.

[sagar1511]

suppose my range is 128 to 255 and my replace value is 170.than all the value between 128 to 255 will become 170.than what happens for the range between 0 to 128?