Here's how to create a film halation effect in Photoshop. First, duplicate your layer. So press Command or Control J. Now go over to Image, Adjustments, and Threshold, and move it towards the right.
Basically, we want to limit what has this effect to only the brightest parts of the photo. So once you have something like this, press OK. Go over to Filter, Blur, and Gaussian Blur.
And here we're going to create the blur effect. Depending on how strong you want the bloom to be, you're going to increase it more or less. I'm going to keep it around here. And at this point, you won't be able to see anything until you change the blend mode to screen. Now you'll see the blur, but there's no red.
Halation typically looks red. So what we can do here is we can go over to layer, new fill layer, solid color, and then select red. Now we want to right click on this layer and create a clipping mask.
And we want to change the blend mode to overlay. Now you can see this effect. And what's great is because we created smart filters, we can just double click on them and we can change them.
You can also change the threshold. So this is what is being blurred. So you can see this is a larger surface area. You can actually go and select your brush and change it to black or white to add or remove collation from certain areas. You can check out our Photoshop Action Pack if you want to check out more Photoshop actions like this.
That's it, follow for more!