(gentle happy music)
Hi, this is Sarah.
Welcome to Day Six of Scratch Art.
Last time we learned about a conditional
called the if statement.
Today you will use another conditional
called if else to make a program
that scans an image and makes a shadow.
An if statement reads,
if a condition happens then do this action.
An if else statement represents an either or option.
If the first condition is met,
then it will do the first option.
If the first condition is not met,
or else, it will do the second option.
For today's project the shadow should be black
if the picture is black,
but otherwise, or else, something still needs to happen.
The shadow should be white.
An if alone wouldn't allow for both options.
Pictures displayed on a computer screen
are made up of millions of little squares called pixels.
When the human eye takes in
all these little squares together,
it sees them as one complete picture.
Computers make it easy to change the look
of a picture or photograph
because they can manipulate each tiny pixel individually.
Apps and photo editing tools, like Instagram,
apply specific digital effects to photos
using a process similar to the one you will use today.
Sometimes called filters,
these effects include making photos black and white,
altering the color scheme,
or selectively changing portions of a photograph.
Editing tools like Photoshop
can reduce red eye,
make a background transparent,
and sharpen images.
The computer tests each pixel in the photo
and changes it to create the different effects.
The if else conditional statement
allows computers to make these effects.
In this example,
the computer applies the selective color effect.
It scans the color of each pixel.
If the color matches the one it is programmed to bring out
it keeps that color,
else it grays out the color.
In this picture the program keeps the vibrant yellow color
while the other colors are grayed out.
These editing tools were created with computer science.
Before these kinds of tools existed
artists had to painstakingly apply color to film
or paint out mistakes.
With computers, these corrections can be made instantly.
In today's project you will program a filter
that scans images to make silhouettes or shadows.
Now it's your turn.
Open the starter project,
click Remix,
and sign in.
Then proceed to the next video.
