In this lesson you will learn how to use the tools we revised
in the previous session. These tools will help you correct,
improve and alter your images. |
Opening
your document
Photoshop can open a variety of formats like: JPG, GIF, PNG,
TIFF, EPS, PICT, to name a few.
To open a file: Go to File > Open..
You can specify the format from the menu, or simple choose Show
All files to display all files in the selected folder.
The first thing to do before starting with photo corrections,
is to identify the format, resolution and size of the image
that you want to work with.
Once you have opened your document in Photoshop, go to Image
> Image Size...
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The Image Size window will specify the Pixel
Dimensions (screen size of the document), as well as
the Document Size (the printing
dimensions).
You can also see the Resolution
of the image. This is important, because it is preferable that
you do your image corrections and alterations in a higher resolution
document (if available). |
The higher resolution of
the image, the better it is for editing purposes. Further
ahead in this lesson you will learn how to bring down the image
to a lower resolution suitable for Web, once you are finished
with your edits.
Note: Sometimes
you might be restricted because of your computer configuration...
If your computer does not allow you to work with a high-resolution
image, then bring the resolution down from the beginning, for
example, if your staring image has a resolution of 300 or 150
DPI, then bring it down to 100 or 72 DPI. Just try to keep the
size of your document larger, your Pixel Dimensions!
Here is an advise: ALWAYS KEEP
A COPY OF YOUR IMAGE SOURCE FILE, specially
if you have a high resolution one. It is good to have a back-up
image that you can work on. At the end of the process of image
correction you will start to compress your file. Compression
takes important data out of your image that is hard to pull
back up, to a higher resolution and quality. |
Save a copy of your
document in the Photoshop format
Go to File > Save As...
> Select PSD from the Format drop-down
> Name your document.
The extension assigned is PSD.
Image
Mode
Go to Image > Mode > RGB
A large percentage of the visible spectrum can be represented
by mixing red, green, and blue (RGB)
Adding all three colors together creates white, therefore they
are also called additive colors. These additive colors are used
for lighting, video, and monitors. Your monitor, for example,
creates color by emitting light through red, green, and blue
phosphors. |
Let's get started correcting your images.
Here is an example of an original image as
you might see it the first time in Photoshop:
As you see in the image, it is overall dark, looks blurry and
has black borders in two sides. |
Adjusting the Image
Levels
The Levels will adjust the
image's key tones: Shadows, Mid tones, Highlights.
Simple way:
Go to Image > Adjust > Auto Levels
Photoshop will interpret the values for the Shadows, Mid tones
and Highlights, and correct the image automatically. You get
a much better control of the image by doing the following, detailed
procedure. |
Detailed way:
Go to Image > Adjust > Levels...
Following is the example of the corrected level graph window
and the result on the image. |
Move the Highlight slider
to the left, to the beginning of the black mark of the histogram.
You will see how the center slide (mid tones) moves along. The
idea here is to obtain a good balance with your shadow levels,
mid tones and the highlights. The levels histogram is a way
of visualizing how your image is balanced. Make sure you have
the preview checked, this way you can see how the image
is being modified. |
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Levels adjustments
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Brightness and Contrast
Go to Image > Adjust > Brightness/Contrast...
Move the slider and adjust the image as you need. In this example
we want to brighten the picture a little. Make sure the Preview
is enabled so you can see the changes.
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Brightness adjustments
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Cropping the image
Cropping is the process of selecting and removing a portion
of an image to create focus or strengthen its composition.
With the example in use, we will eliminate the left and bottom
black borders, and find a better angle of the picture.
You can crop an image two ways.
By using the cropping tool:
1. Select the cropping tool from the toolbox.
2.Drag over the part of the image you want to keep. When you
release the mouse button, the crop marquee appears as a bounding
box with handles at the corners and sides, and a cropping
shield covers the cropped area.
3.Adjust the area with the handlers.
4. To crop the image, press Enter (Windows). Double click
on the marquee area or click the OK button in the options
bar.
5. To cancel the cropping operation, press Esc.
 By
using the Selection tool:
1. Select the Rectangular Marquee from the toolbox
2. Select the area that you want to crop
3. Go to Image > Crop
This method is less precise but fast.
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Cropping with the crop tool
Cropped Image
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Re-sizing
the image
Once you are finished with retouching and correcting your
image, the next step is to prepare it for its final size in
a Web page.
Remember that when we started working on the sample image,
we left the document with a large Size and Resolution. This
was done intentionally in order to have the best quality while
doing the alterations. Now it is the time to re-size it to
the specific size that you need it.
Check your HTML layout and decide upon a reasonable size for
your image. Pick a size that will not be either too small
or too large to un-balance your composition.
When preparing images for Web you need to specify image size
in terms of the pixel dimensions. Keep in mind that changing
pixel dimensions affects not only the size of an image on-screen
but also its image quality and its printed characteristics.
To change the pixel dimensions of an image: |
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1. Choose Image > Image Size
2. To maintain the current proportions of pixel width to
pixel height, select Constrain Proportions.
3. Under Pixel Dimensions, enter values for Width
and Height. To enter values as percentages of the
current dimensions, choose Percent as the unit of measurement.
The new file size for the image appears at the top of the
Image Size dialog box, with the old file size in parentheses.
4. Click OK
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TIP:
For assistance with resizing and re-sampling images in Photoshop,
choose Help > Resize Image. This interactive
wizard helps you scale your images for print or online media.
Keep in mind that bitmap data can
produce different results when you resize an image. Bitmap data
is resolution-dependent; therefore, changing
the pixel dimensions of a bitmap image can cause a loss in image
quality and sharpness! The next step is going to help you bring
back some of the sharpness to your image that was lost during
the re-sizing.
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Sharpen
Simple way:
Go to Filters > Sharpen>Sharpen
This action will set a default percentage to your image. It
is a quick fix and it works for some images. If you need the
sharpening to be more settled, than do the following step.
Detailed way:
Go to Filters > Sharpen > Unsharp Mask...
Manually change the sharpen Amount, the Radius
and Threshold with the sliders. Both the
Radius and the Threshold are very 'sensible' items. Moving
the radius too high, might darken the edges of the image,
while increasing the Threshold will reduce the area to be
sharpened.
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Before
After
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Editing in Photoshop