How to reduce contrast of Histogram equalized image

Hi, I performed histogram equalization on thermal gray scale image.

load image.mat;
a = vidFrame2;
figure;
subplot(2,2,1),imshow(a),title('original image');
subplot(2,2,2),imhist(a),title('Histogram of original image');
b=histeq(a);
subplot(2,2,3),imshow(b),title('Histogram equivalized image');
subplot(2,2,4),imhist(b),title('Histogram of output image');

I have attached the output image. The output of histogram equalization gives a very high contrast image, where the minute details of the image is lost. How to do histogram equalization with correct contrast.