(upbeat music)
- [Julieanne] In order to change the size of a document
for a specific output device,
we'll use Photoshop's image size command.
I'll choose Image, and then Image Size,
or we could use the keyboard shortcut
Command + Option + i on Mac
or Control + Alt i on Windows.
On the left-hand side, we have a preview area,
and we can click and drag in order
to view different areas of the image.
And on the right-hand side,
we have all of our image dimensions.
We can also expand this
if we wanted to see our preview area a little bit larger,
or we can also preview this in the image area.
But if you're going to do this
for the most accurate viewing,
you'll want to be zoomed into 100%,
so I'll use Command + 1 on Mac or Control + 1 on Windows.
Now, we can see that the original image size here
is a little over 24 megs,
and the width, height, and resolution
are 12 x 8 x 300 pixels per inch.
Now, as I start making changes,
there are two different ways that I can do this.
I can either choose to re-sample my image,
or I can toggle this off.
If I turn off re-sampling
and then I make changes to the width, height, or resolution,
we can change the print size of the image,
but we're not actually re-sampling.
We're not adding or subtracting pixels.
We're just determining how many of them we want Photoshop
to put in a specific unit of measurement.
So for example, if I decide
that I want to change the width from 12 to 18,
well, Photoshop isn't going to have as many pixels per inch.
We can see the resolution drops to 200.
If I only need to print this six inches,
then Photoshop can add more pixels closer together,
and my resolution moves all the way up to 600.
If I toggle on the re-sample option,
now, I'm allowing Photoshop to either discard
or make up information
as I change the width, height, and resolution.
So for example, if we take this back up to 18 inches,
and I want to print it at 300 pixels per inch,
now Photoshop is going to make up information,
taking what was that 24.7 meg file up to a 55.6 meg file.
If we ever want to see how much
or what percentage Photoshop has to resize the image,
we can click and change this to percent.
So now I know that Photoshop has to make up a half a pixel
for every original pixel that was in the document.
If you want to control how the image is re-sampled,
you can select from a number
of different re-sampling options.
If you choose Automatic,
it's going to select the Preserve Details
when it's enlarging or adding pixels to the document.
And it's going to select by cubic sharper if it has to reduce
or discard information from the document.
The nice thing is is that you can leave it set to automatic,
and Photoshop will automatically select the option for you.
If you want to try out any of the other options,
please feel free.
I like the Preserve Details.
It's a tech preview,
and it detects and preserves detail and textures and images
without over-sharpening prominent edges
or smoothing out the lower contrast details.
And I think it works really well
with harder-edge details like texts and logos.
So let's take a look at how I would set up image size
for three specific output devices.
If I need to resize this for a specific screen,
then I would change the units of measurement to pixels
and just enter in the number of pixels that I need.
Or if I was going to the printing press,
then I would change this back
to the units of measurements that I wanted to use.
And let's say I was going to a 150-line screen,
so I'd multiply that by 1.5,
and that would be 225 pixels per inch.
Now, let's decrease the inches down to 18 inches,
and we could see that Photoshop would need to add
or increase this 112.5%
in order to print with those dimensions.
Now, the third example would be either the inkjet example
where I'm printing at 300 pixels per inch,
or let's say I was sending this to a lab
to print continuous tone,
and they requested 300 pixels per inch.
Well, then I would just change this to 300 PPI,
and let's say I wanted to print it out
at six inches by four inches.
Now, we can see that Photoshop would need
to decrease the file size.
For now, I'll click OK,
and we can see that Photoshop makes the file smaller.
I'll use Command + 0 in order to fit on screen.
And then I would most likely want to save
a copy of this file at the new size,
so that if I ever needed to return to the original document,
I would still have that full resolution file.
But for now, I'll go ahead and just close it without saving.
So there you have it.
You can use image size in Photoshop
to resize your photographs or your images
for your specific output devices,
deciding whether or not you want to add
or remove information using the re-sample option.
(gentle music)