How can I convert gray image to binary image on ”specific” value of luminescence

I want to make binary image to analyze my gray scale image.

I know there is im2bw function. But I want to select certain color values associated with specific luminescencce

For example, when we convert image to binary image, we designate certain threshold value, such as we designate threshold value as 0.4, luminescence lower than that value turned to black and higher than that value turned to white.

However, I want to convert grayscale image to binary image of selecting the "range" of luminescence, such as I want to turn convert the area has the range between 0.1 and 0.4 too black. and below 0.1 and over 0.4 should be convert to white. That`s because I want to analyze the objects of certain brightness only.

Could you give me appropriiate way for me?

post the example of grayscale image.

Answer 1

[Guillaume]

It's simple comparisons and logical operations:

• lower than 0.4 to black, higher to white (what about 0.4?)

result = yourgreyimage > 0.4;

• between 0.1 and 0.4 to black, the rest to white:

result = yourgreyimage < 0.1 | yourgreyimage > 0.4;