How can I make the Background of an image invisible? (R2018b)

When I start to plot the image with imread, the image is plot with background. How can I set this background invisible or how I can delete the background?

I tried:

auto = imread('Auto.png', 'BackgroundColor','none') % this code not worked

and I also tried to cut (delete) the Background in other Programms.

Thank you for your help

[Johannes Fischer]

Its a bit hard to guess what exactly you want. Do you want to make the background of the figure invisible, in which the image is displayed, or do you have an image - lets say a person on the beach - and you want to delete the beach in the background?

An example image would be helpful.

[KALYAN ACHARJYA]

Please do share Auto.png image.

[Michael Dornseifer]

@Johannes Fischer

The second option: I have a image and want to delete the background.

The Image is like the auto.png.

I only want the car, without the white background.

[Johannes Fischer]

auto  = imread('auto.png');
% create an alpha channel where the image is more transparent the brighter it is 
% (only works with greyscale RG images, as im only using the red channel here) 
alpha = 255 - auto(:, :, 1);
% make the lines a bit darker
auto(auto < 220) = 0;
% save image with alpha channel
imwrite(auto, 'auto_tp.png', 'Alpha', alpha)

Answer 1

[Mahesh Taparia]

Hi,

As per your image, it will be a two-class classification problem in an image. Since the image is a black and white and you want to extract the black pixels, it can be done by converting the image into gray color space and then using Otsu’s thresholding method by using 'multithresh' function to set proper threshold.

You can do so by executing the following lines of code:

auto = imread('auto.png'); 

Gray_img=rgb2gray(auto); 

thres=multithresh(Gray_img); 

Segmented_img= Gray_img <thres; 

figure;imshow(Segmented_img) 

imwrite(Segmented_img, 'auto_segmented.png')