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I happened to already have a number of photos of flames that I had shot in the past, but shooting your own is not too difficult. I photographed mine inside my fireplace, right in my living room. Just keep in mind that you want the flames to be on as black a background as possible, so film them after dark with the lights out for best results. Expose for the flames, and the surrounding areas should come out pretty dark. Also, let the fire burn for a while first. You want to still have flames, but the more seperated they are the better it is for our purpose. One big raging inferno is difficult to work a texture out of.
Here is one of the pics I used, so you can use it to go through the tutorial.
There are actually two nice flame shapes in this image, but I really like the one on the right. So the first step is to crop the picture down to the part you want. Use the rectangular marquee to select the area, then go to Image > Crop.
EffectsLab and VisionLab ultimately use all texture files at a resolution of 512x512, so it is best to create your files in either that size, or to use 256x256 or 128x128 if you want to keep the file sizes smaller. Really only highly detailed textures need to be full resolution. (As these are photo-real, I keep the resolution at 512x512.) All textures should be created at 72 dpi.
So, now to make our image the right size. Go to Image > Image Size. Set the Resolution to 72 pixels/inch. Set the height of your image to 512 pixels, making sure that Constrain Proportions is checked on. Before you click OK, it should look like this:
Now our picture is the right height, but it is too skinny. We don’t want to leave it, or our flame will get stretched when the texture is used in our effects. We want to add black to the sides, so our image is the right dimensions, but the flame retains its shape. Set your background color to black. Then go to Image > Canvas Size. Change the New Size width to 512 pixels. Keep the anchor centered. Then click OK.
Now we need to make sure that all of our black is truly black. Image > Adjustments > Levels will give you the levels controls. Tweak the left slider in the input controls until it is just to the right of the black spike in the histogram. (I set mine to 22). Some of the midtones can be brought back by sliding the center slider a bit to the left. You can play with these numbers to get a look you are pleased with. It should look something like this:
All texture files will get colourised when you apply them to particles, so it is best to use greyscale images. All we have to do is desaturate. Go to Image > Adjustments > Hue/Saturation to open the window, then slide the Saturation control all the way to the left to -100.
Now we have a nice grey flame. We may have a few unwanted bits around our flame left over from the original image. Grab a black paintbrush and paint them out. Here are a couple areas that I painted out.
If you need to paint quite close to your flame, remember to use a very soft brush, and obviously be careful. Now we have the flame looking just the way we want.
The last thing to do is add an alpha channel. Here’s an easy way to take care of this in Photoshop. Go to Select > Color Range in the menu. Set the drop-down menu to select Sampled Colors, then use the pipette to click in the black area of your image. Slide the Fuzziness control way over to the right. I went all the way to 200. You will be left with what looks like a negative of your image in the preview window. Like this:
When you click OK all of the black in your image will be selected.
Now go to Select > Inverse. This will select only the flame, the parts of the image you want to see in your texture. Copy and paste. when you paste , it should create a new layer in your image. Once you have the flame pasted onto a new layer, delete the background. You will be left with the grey shades of your flame over a checkered background. This is your texture file.
You will notice that it is a relatively even shade of grey throughout. Sometimes, for some effects, this will work well. But for our purposes, to create a realistic flame, generally there are various shades and colors involved, so we will want to add a bit morre contrast in the greyscale image. Use another Levels command to do this, bringing the sliders in from either end until they meet the ends of the black area of the histogram.
That's looking a lot better.
Now we can save it. File > Save As... and give it a name. Save it as a PNG or TGA (Targa) file. This is important becaouse there are only certain formats that will support the alpha channel info we have created. Now you can move it to your textures folder and you are ready to try it out.
With any texture file you can greatly simplify the alpha channel process by simply painting your texture onto a layer other than the background, which is essentially what we did here, although we used a photo source rather than painting. Any transparent areas on the layer will remain transparent when the texture is applied.
When Add composite is used on texture files within the particle effect controls, and black areas will disappear automatically. But by creating your textures with proper transparency built into them, you will ensure that they can be used in a much greater variety of effects.
When you create a particle effect, or a muzzle flash, you assign a color to the texture files you use. the greyscale within the texture images controls how they respond to the colourisation. Pure white areas (RGB 255,255,255) in the texture will remain white. Pure black (RGB 0,0,0) will stay black. Other than that, the amount of grey in the pixel determines how much color it will receive. If your color is red, for example, then dark grey areas in your texture will become dark reds in your effect, and light greys will become light reds.
Knowing this, you can adjust your texture files accordingly. Say you wanted to make the flame texture from the tutorial much brighter. You could use the Levels controls to increase the whites in the image, by sliding the right-hand triangle over to the left a bit. This will increase the brightness of the highlights within the image, resulting in their retaining more white, and thus more brightness, when applied as a texture.