By Zach Goldstein
In this tutorial, you are going to learn how to do a neat trick using Blender's powerful Sequence Editor. The Sequence Editor can do a lot more than what I am going to show you here, but this tutorial will get you more familiar with using it. We are going to do what I call "Merging images." Basically we will take two JPEG images and merge them into one image in the Sequence Editor. This process is actually quite easy. Yes, I know it can also be done easily in 2d apps such as Adobe's Photoshop and The Gimp. But it can also be done in Blender, as you shall see.
I learned how to merge images in Blender while I was making a model of an F1 in order to participate in the annual Blender F1 Challenge in 2005. You can see my entry in the 2005 contest page. I placed the F1 model on a concrete island in the middle of the ocean inside a giant glass skydome with a futuristic planet scape on the horizon. I used Raytracing for the skydome glass in order to make it reflective. But I also put a horizon mist on the edge of the ocean horizon to simulate depth. Unfortunately, mist cannot be seen through Raytraced materials. Both the window reflections and the horizon mist were important elements of the scene, so I couldn't just drop one. So I had to figure out a way to use both. One member of the Blender community at elYsiun.com with the alias Sonix suggested I try merging two images together in the Sequence Editor. He said to render one image without Raytracing and use mist, and render a second image with Raytracing and without mist. Then merge the two.
This sounded like a good idea and I decided to give it a shot. Because you couldn't use Photoshop in the contest, this was the only way I could do it. But there was just one problem. I couldn't find any tutorials on how to do it. Sonix didn't know how either, but he gave me a link to a tutorial written in Czech. But because I can't read Czech, the tut didn't do me much good. But I was able to get enough from it to figure out the basics, after playing around with it for an hour or so. Because I liked this feature so much, and the only tutorial I could find was written in Czech, I decided I would write up a tutorial myself in English so more people could learn how to do this. So here it is. Now let's get started.
Ok, now that you have done that, look to the far left of the screen. You will notice the current window type button. Press that and select the "Video Sequence Editor" link. That will bring up a gray screen with a large grid. We are now going to load the two images you downloaded above. Press Shift + A; you will see menu named "Add Sequence Strip" appear. Select the "Images" link and browse your computer for the image files you downloaded. NOTE: IT IS IMPORTANT THAT YOU KNOW WHERE YOUR IMAGE FILES ARE SAVED. YOU NEED TO BE ABLE TO FIND THEM TO COMPLETE THIS STEP. Once you find the first image you wish to use, click on it and hit the "Select Images" tab up in the top right-hand corner. When you do this the menu window will disappear and your mouse will control a 50 frame tab containing the selected image. Move that tab to the far bottom left corner and left click to leave it there. Repeat the above mentioned process, only this time selecting the second image. When you select the second image, move its tab onto the layer of rows just above the first image and click to keep it there. You now should have two 50 frame image tabs with the second tab above the first in the bottom left corner. Now select both tabs at the same time by holding down Shift and right clicking. Now Press Shift + A again. This time, however, select "Cross." Move the Cross tab in the 3rd row just above the second image tab. NOTE: YOU MUST SELECT BOTH IMAGE TABS BEFORE YOU CAN ADD A CROSS. This is what your Blender window should look like now:
You have now set up the two images and they are ready to be merged. Now left click anywhere inside the window. When you do this you will notice a green vertical line crossing both image tabs and the cross. NOTE: EVEN THOUGH YOU CAN MOVE THE GREEN VERTICAL LINE ANYWHERE INSIDE THE SEQUENCE EDITOR WINDOW, YOU NEED TO KEEP IT SOMEWHERE INSIDE THE IMAGE TABS. Ok, now left click and place the green vertical bar in the MIDDLE of the tabs. It should strike through the middle of the image tabs and the Cross. The position of the green bar determines the strength at which the images merge. If you move the green bar all the way to the left, you will see only the second image. If you move the bar all the way to the right of the tabs, you will see only the first image. If you move the bar to the middle of the tabs, you will see an equal amount of both images. This is nice because it gives you a lot of control over the images. For now, just put the bar in the middle as mentioned above.
Now let's take a look at what we have just done. To do that, look in the window bar for this button, . When you press that a black window will appear with the merged images in it. And there you have it. If you did everything correctly you should see that your two original images are now combined into one single image. You can play around with this more by moving the green bar to different positions on the screen. Once you get the image to look the way you want, you can save it as a JPEG to your desktop. This is why I told you to activate the "Do Sequence" earlier. This tells Blender to look for an image in the Sequence Editor rather than a previous render. Press F12 to see a the full view of your merged image. Now press F3 and save the image where ever you like. Don't forget to type the image file extension after you type the name.
Well, there you have it. I hope that as you read this tutorial, you learned something new and came to appreciate even more the amazing features of Blender. Blender's Sequence Editor truly is an amazing tool. If you would like to learn more on how to use it, visit this link. I will be writing more tutorials soon, so keep an eye out. Happy Blending.