Want to resize WordPress image to fixed height and auto width? As this was specific wordpress question and I found an answed, i will share it. When you add custom image size to functions.php, add 9999 to width and hardCrop to false.
add_image_size('slider-thumb-alt', 9999, YOUR_FIXED_HEIGT, false);
If you like this question & answer and want to contribute, then write your question & answer and email to freewebmentor[@]gmail.com. Your question and answer will appear on FreeWebMentor.com and help other developers.