How to define a general affine2D transformation matrix for all handwritten images and rotate them as needed.?

I used the following code to generate img2 from img1 but when I run the code on another image, I have to change the affine2d matrix according to each image manually... I want a code that is general for all images so that if they have slant angle more than 0 then the resulting image should have the slant angle 0. I used imwarp function for this purpose...

[filename,pathname] = uigetfile({'*.jpg;*.jpeg;*.png;*.bmp'},'File Selector');
name = strcat(pathname,filename);
img = imread(name);
img = imcomplement(img);
img = rgb2gray(img);

figure()
imshow(img);

tform = affine2d([1 0 0; 1 1 0; 0 0 1]);
J = imwarp(img,tform);
figure
imshow(J)

Can anyone help with the code?... Thanks in advance!

[Matt J]

How are you defining/computing slant angle?

[HJ Akhtar]

I didn't... I just randomly assigned the value to matrix I don't know how to compute it.. and if got, how to define affine2d matrix on the basis of that angle

[HJ Akhtar]

Can you please tell me how to do it? Code example will be appreciated.. Thankyou