Feet and Inches to Pixels for a matte

[Aaron Neitz]

You can’t until you have the footage in your hands. The pixels will be determined by 1) the lensing and range on the camera and 2) the video resolution you’re working at (including those pesky D1 frames). A 300′ screen could end up 20 pixels across if they shot it from way-way back.

However given a specific dimension, you can create a rectangle or square or whatever in those proportions. So 37′ by 17′ could equal 3700pixels x 1700pixels. And then hopefully they shoot it dead on.

[Gary Hughes]

I assume you are making the mask so that the videos you provide will project correctly on his screens. If so AND if you are using a square pixel format in editing, there’s a very simple way to do it in Photoshop, and you can even somewhat automate it with actions. A non-square pixel format, such as NTSC, would require one more step to compensate for that difference. I’ll assume that you’re using some form of HD since your screens are so large. Since I don’t know exactly what resolution you work in, I’ll use 1920 x 1080 in my example. If you use a different resolution, simply replace my numbers with yours.

• First, your sizes must be in “like” formats. In other words, your example is 8′ x 100 yards. Convert it to 8′ x 300′.
• Create a new Photoshop document that is 8 inches by 300 inches at a resolution of 72. Use black for the background color.

Each step from this point on can be automated by creating an action. Let me know if you aren’t familiar with actions and I’ll tell you how to take advantage of them.

• Under the File menu, choose Automate, then Fit Image.
• In the entries, type 1920 for width and 1080 for height and click the OK button.
• Type D on the keyboard to set your colors to the default black and white.
• Type X to swap the foreground and background colors, so that black is in the background swatch.
• Create a new layer above the background layer and fill it with white. Option + Delete on a mac and Alt + Backspace on a PC.
• Under the Image menu, choose Canvas Size.
• Change the measurement type to Pixels and enter 1920 for the width and 1080 for the height and click the OK button.

If you are using this as an alpha matte, then simply flatten it, then stop the action recording and save your file. If you need the center to be transparent, then continue with the following:

• Select the filled pixels in the top layer. The shortcut is to hold down Command while clicking on the thumbnail of the top layer in the layers pallet.
• Name the background layer by double clicking on the word Background in the layers pallet. This converts it to a layer which allows transparency. It doesn’t matter what you name it.
• Press the Delete key on your keyboard.
• Delete the top layer. You don’t need it anymore.
• Stop recording your action and save it as a tiff with transparency.

To do other screen sizes, simply do the first two steps above using the new dimensions and then run the action.

Hope this helps,
Gary