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T354 - Week 3 - Spring 2014

Notes/Announcements:

  • Don't forget to order your book. You'll need it next week. This is the last week dedicated to Photoshop.
  • You'll also need your portable USB hard drive.
  • Remember clip art is not allowed - make sure your work has artistic and legal integrity.
  • Remember CRAP! Use contrast to draw attention to your message. Repeat visual elements, Use alignment to create order. Place corresponding elements in close proximity to each other.
  • Photoshop Quiz in one week (Next Tuesday)

Agenda:

  • Look at and critique artwork
  • Alpha Channels
  • In-class exercises

Photoshop (continued)

Video monitoring & output

No matter what colors or brightness levels you use in Photoshop, the images you create on your desktop will always look crisp and sharp on your computer monitor. Unfortunately, in the real world, graphics for TV are often output to video, compressed, stored on tape, played back, uplinked, downlinked, aired and finally received and viewed on a TV set. When we finally see them on TV they look quite different from the original computer output display.

To ensure their images will appear properly on TV and that brightness levels are in the legal broadcast range many professional graphic artists often work with real-time video output and a waveform monitor. You never really know how your work is going to look unless you view it on an actual TV screen (not just your computer monitor). Don't feel confident that your work is ready for prime time until you see it first, composited with video on a TV/broadcast monitor. and see the output levels on a waveform monitor.

Some companies make real-time video output devices so you can see your Photoshop or After Effects composition on a video monitor while you work. AJA, and BlackMagic both make IO devices for Apple and PC computers.

If you are serious into editing and making graphics get an Ultrascope (by BlackMagic).

Even Adobe's After Effects, and Apple's Motion and Final Cut Pro let users output and view their work in real-time through the firewire port. In other words, you can hook up a camcorder or deck with a firewire cable to view your work on a video monitor connected to your gear.

Channels and Alphas and Bits, Oh My

Video and computer graphics are usually created in the additive color system using three colors: Red, Blue and Green. In Photoshop you can easily see this in the channels window. In fact if you toggle the three channels on and off you may even come to understand that they can be seen as three separate black and white images.

Color channels are created automatically by Photoshop when you make a new document. The color mode determines the number of channels. When you start a new RGB image, it creates three channels, one for each color plus a composited RGB channel. If you make a new file in a CMYK color space, Photoshop creates four channels (Cyan Yellow Magenta & Black) plus a composited CMYK channel.

You can view your channels in your image by looking at the channel window in the lower right hand corner of your screen. If you can't see it select "Windows -> show channels"

Masks let you isolate and protect areas of an image. They work like stencils. When you select part of an image (say with the magic wand tool) the area that is not selected is masked, or protected from editing.

Quick Mask mode lets you create, view and edit a temporary mask for an image. The good thing about editing your selection as a mask is that you can use any paint tool to modify your selection. You can enter Quick Mask Mode by clicking on the button near the bottom of the toolbar.

When you paint with black, you are adding to the mask. When you paint with white, you subtract from your mask.

Masks and selections can be permanently stored with your artwork by saving them as alpha channels.

Alpha channels

Alpha channels can define parts of an image to be transparent. These channels aren't typically meant to be looked at (or appreciated) by the viewer, but are used to define the transparency of another image or the other color channels. To understand this, it helps to quickly review bit depth. Bit depth or pixel depth refers to how much color information is in a particular image. 8-bit images contain up to 256 colors or shades of gray (like a GIF graphic). 16-bit images can have thousands of colors and 24-bit images more than 16 million.

The RGB files you create in Photoshop have three 8-bit channels. (3 x 8-bit = 24-bit).

An alpha channel is another 8-bit channel. Think of it as an extra black and white image stored along with your graphic. To make one, simply save a selection or a mask as an alpha channel. In Photoshop you can save selections as alpha channels by looking under "select" -> "save selection". Or you can go to the channel palette and click on the "save selection as a channel" button.

Look at an example of a lower third graphic with an alpha channel. (other sample files: jon.tif and lower_third_temp3.psd)

  • Black is transparent
  • White is opaque (visible)
  • Gray is semi transparent

Since it's an 8-bit channel (think grayscale image), you have 256 steps from black to white. That's 256 varying stages from opaque to transparent.

Adding this additional 8-bit information to your 24-bit image creates a 32-bit image.

An image can have up to 24 channels. (Color or alpha channels) So it’s possible to save multiple alpha channels for varying applications. But while you can have multiple alpha channels in a Photoshop document, a PICT or TIFF file made to import into Final Cut Pro can only have one alpha channel.

In class exercise (4 pts):

  • Download the zipped file of interview stills.
    • Open them in Quicktime Player and note their codec and pixel dimensions.
  • Open Premiere or Final Cut Pro. Make a new project and import the jpeg.
  • Note: If you were actually editing a video project you'd have to make sure your Scratch/Media drive are set to the right place. In the future you'd set this to be your external hard drive.
  • Import the jpegs into your project.
  • Make a simple keyed graphic in Photoshop to import into your HDV project (1920 x 1080). Call it "simple" and make a PNG or TIFF version with an alpha channel.
  • Save the "simple" graphic into your Oncourse Week3 folder.
  • Import this into your project. How does it look?

Thursday ---------

Straight & Premultiplied Alpha Channels

Alpha channels can be saved as straight or premultiplied.

Straight (also known as unmatted) relies solely on the alpha channel to determine opacity.

Premultiplied (also known as matted) store information in the alpha channel, but also factor in transparency information into the R, G & B channels. In premultiplied files, the nicely feathered semi-transparent edges will become mixed with the background color.

Programs like After Effects interpret alpha channels as either straight or premultiplied. Using the wrong interpretation or premultpilying with the wrong color can result in undesirable white fringing or halos around the perimeter of the alpha.

Using Photoshop's Actions to create an alpha channel:

In Photoshop you can easily make an alpha channel by using the Actions palette. Actions are a prerecorded series of steps you can use that make lengthy procedures simple. Here's how to create an alpha channel using them:

  • Make sure that only the layers you want are visible.
  • Open the Actions window.
  • Open the "Video" actions (accessed by the tiny top right arrow menu).
  • Select "Alpha Channel from Visible Layers" .
  • Press the PLAY button at the bottom of the window.

Examine the sample headshot and lower third graphic found here. Note that the horizontal highlight bar is semi-transparent. Examine the corresponding alpha channel.

In-class exercise (6 pts):

  • Create a nicely designed 1920 x 1080 keyable lower third ID or title graphic.
  • Make sure it has at least two uses of text, at least two other design components, and something that is partially transparent.
  • Create an alpha channel that keys nicely (with no white fringing).
  • When you are finished, save a copy as a single-layer TIF version with a single alpha channel into your folder in the "Week 3" folder named "alpha". Make sure it is called "alpha".
  • Composite the graphic over video or a stll headshot in Final Cut Pro or Premiere. How does it look? Output a JPEG frame from the timeline to put into your Week3 folder. Make sure it is called "still".

Vocabulary

  • Codec – Short for coder/decoder or compressor/decompressor. Manufacturers have unique, sometimes proprietary ways to compress, store and retrieve digital files. Examples include DV, JPEG, Avid, and MPEG.
  • Serif - This is a detail found on the ends of the various strokes that make up a typeface. Examples of seriffed typefaces include Times, Courier and Bookman. This sentence uses a seriffed typeface. Most editors and typesetters think that large printed blocks of text are most easily read using a seriffed font.
  • Sans Serif - Fonts that are sans serif (without details) include Arial, Verdana, and Helvetica. Almost all of this page uses a sans-seriffed typeface.
  • Opacity - (the level of transparency. Objects that are 100 percent opaque are solid, objects that are 0 percent opaque are transparent.
  • Alpha channel – (see above)

Homework (Due at the beginning of next week's lab):

You have been hired by a production company to design a package of graphics for their new TV talk/news/magazine show, which is being produced in HD. They want you to make a title graphic, a graphic to promote the show, and a lower third key graphic to ID their guests with. The company has requested TIFF versions of each graphic at 1920 x 1080.

There should be visual and artistic consistency between the three graphics. For instance if you use a yellow crescent moon over a deep blue background in the title, you might consider adding that as part of the lower third to ID the host with.

Remember- the design elements need to come from you! In other words please don't use other people's images or artwork in your design.

  • Title Graphic: The title is used to open the show. This graphic needs to contain at least two separate pieces of artwork or images, and any text you want. Please call this "title".
  • Promo Graphic: This will be used in an ad to promote your show. It should contain the vital information you'd expect to see in a promo: plug (reason to watch), title, time etc. The message should be clear & easy to decipher. Please call this "promo".
  • Lower third video graphic: This keyable graphic will be used to identify a guest or the host of the show. Your TIFF file should have a clean alpha channel in it. Please call this "key".
  • Critique form: Since these graphics will be similar in style, you can use one critique form for all three graphics. Be sure to keep the original PSD file, as we will likely use these in lab.

Here's an example (these are 4x3, yours will be 16x9):

Promo

Title

Lower third

Note that the colors and font treatment are similar. All of these images also share the purple blob element.

Don't forget to study for Tuesday's Photoshop Quiz!

Starting next week we'll start After Effects. Don't forget to get the book "Creating Motion Graphics with After Effects, 5th Edition". You'll also need a portable hard drive in the coming weeks. (At least 250 GB is recommended.)

 

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