Open a new file in Photoshop.It should be 5100x3300 pixels with a resolution depth of 300dpi.This size is perfect for keeping as much details as possible.
Unlock the background layer by double clicking on the layer thumb and using the Paint Bucket tool (G) select black as your foreground color and fill the layer.
Drag the Tiger stock image to your canvas.Using the Pen tool (P) we are going extract the animal from the background.Draw the path a little bit inside of the tigers face.We don't need to be specifically exact here because we are going to draw all the hair we cut out again.
Once you close the path, right click and select:Make selection. On the feather radius use an amount of 10 pixels.This feather will make it easier for us to blend the hair we are going to paint on the sides of the face.
Now we are going to manipulate the head to deform it so that the tiger appears more symmetric and so it has a double snout that goes with our psychedelic concept.Select the head layer and duplicate it. Then go to Edit>Transform>Flip Horizontal.
Add a layer mask on the duplicated layer and using a soft (0% hardness) medium (300 px) Brush (B) with Black selected as your foreground color,paint over the left side of the face to reveal the other layer under it until both faces are blended.
Select both layers and merge them together (Ctrl+E). Now we are going to do a few adjustments to the tiger face before we add our gradient map and star painting over it. Go to Filter>Sharpen>Sharpen and apply the filter 3 times (Ctrl+f) to remove most of the blur on the image.
Now add some contrast by going to the menu Image>Adjustments>Brightness and Contrast and apply the next settings:
Our image now has better contrast but still need to be darkened a little bit more.Go to Image>Adjustments>Levels (Ctrl+L) and apply these next values:
I suggest you play around with this settings to get different results when adding your gradient layer because it will act directly on how dark or bright the image is.
Create a new Gradient Map layer (Layer>New Adjustment Layer>Gradient Map) on top of the head layer and click on the Gradient to go to the Gradient editor menu.
I selected a cold color palette I thought would go nicely with the theme (Black for the shadows #000000, Dark Blue for the midtones #04225e and a bright green for the highlights #62e121).I suggest you experiment using very contrasting colors to get a trippy feeling on the illustration.As we go along with detailing the illustration,we are going to use different variations in tone of this same colors.
We need to clip mask the Gradient Map layer to the Tiger head so the effect is only visible on that layer and to do that we are going to click between the two layer thumbs while holding Alt to clip mask them:
This is how the tiger head should look like with the gradient map clip masked: