First of all, collect some images as follows
1. Light Bulb
3. (optional)- I chose this image since I wanted to add the water bubbles which were absent in the 2nd image.
If you carefully observe the final output, it is simply made up of the highlighted part in the following source images...
Luckily there was no color difference in 1st & 2nd images..In case of difference in color, Use Image->Adjustments->Match Color option to match the color
Open a new File.
Select appropriate dimensions that shall suite your source images...
Keep the bulb image on layer 1 as shown..
Now place the image of fishes on layer2. Place this layer below layer 1..Position the image as shown..For convenience, I have switched off the layer visibility of layer 1(bulb) by clicking on the respective eye in the layer window.
Enable the layer visibility of layer 1(bulb) by again clicking on the same eye box..
Reduce the opacity of bulb layer to 50% so that both layers are partially visible.
Adjust the arrangement of both layers with respect to each other.
Note that Intersecting part shall be visible in the output...
Select layer 1, click on the 3rd option in the layer window(Add layer mask). As soon as you click "Add layer mask", you will notice a layer mask thumbnail(white rectangular box) linked with layer 1.
If you click on the brush tool, there will be black & white colors in foreground & background color pallets by default.Make sure that black is your foreground color.
Increase the opacity of layer 1(bulb) to 100%.
Layer 2(fishes) would be completely hidden now..
Select any circular brush, reduce the hardness of the brush to 0.
Make sure that opacity of brush is 100%.
Paint on the mask selected by red boundary so that underneath layer(fish) is revealed.
The major advantage of masking is that if by mistake you paint more than necessary area, you can always optimize it by just selecting white as foreground color and painting on mask, thus regenerating the previously deleted part.
You can see the corresponding changes (white and black color) on the layer mask thumbnail(linked with layer 1).
Now set the opacity of brush to 75% & paint the mask at the base area of bulb(marked in red).
You may change the opacity as per necessary.
Reduce the opacity to 60% and paint the remaining middle portion(marked in red)..While painting make sure that black is selected as foreground color..
Now to obtain the "Glowing effect" of bulb, make following changes..
Change foreground color to white.
Reduce opacity to 30%(you may change as per your wish).
Paint the filaments of the bulb(circled in red) so that they glow a bit.(Note this glow effect is because the original image of bulb had this effect..I am just regenerating the glow by reducing opacity)
The result is almost achieved...All that is remaining is the water bubble effect.
Cut the water bubble part from 3rd source image & paste it on a new layer (Layer 3) in our image.
Make sure that you place this layer in between layers 1 and 2.
Again the same procedure...
Select layer 3(water bubble)
Click "Add layer mask"
Make sure that brush tool is selected & black is foreground color.
Set opacity of brush to 100%.
Paint the unwanted mask i.e. paint the entire area except the bubbles..
Highlight the bubbles by selecting white color, reducing the opacity & painting the bubbles on the mask..i.e. regenerating the image.
And we are done....So fishes do swim in bulb, rite eh?
This was my first ever tutorial.. I apologize for spelling or any other unintentional mistakes...Please let me know if there are any areas in the tutorial which I should improve upon..Feedback appreciated...
I promise that not a single query will remain unanswered..
Let me know if you have queries after going through this tutorial..