Learning image retouch with Photoshop CS6 with 100 practical exercises

14

Resizing an imageDIGITAL CAMERAS TEND TO PRODUCE large images even with

a resolution that could be considered low in comparison to its

size. The resolution, which is normally set at 72 ppi (pixels per

inch), is sufficient if the images are to be viewed on a computer

screen, but insufficient if you want to obtain hard copies via ink

jet or laser printers. With Photoshop it’s possible to reduce the

size of a photograph while at the same time increasing its resolu-

tion and maintaining the picture quality.

1. We recommend using a photograph that fulfills the charac-

teristics mentioned in the introduction. (You can use the ex-

ample image 001.jpg.) Open your Photoshop workspace and

choose an image you would like to resize.

2. Go to the Image menu and select Image Size. 1

3. In the dialog box Image Size you can find the image’s di-

mensions and resolution. 2 Make sure that you really want

to change the resolution of an image because changes could

cause the image to become out of focus, blurred, or pixelated.

This effect is caused by an automatic function of the program

called resampling of the image, which sometimes changes the

dimensions disproportionally to its resolution. Therefore, be-

In Photoshop CS6 it is possible to change the color of the renewed interface by clicking on Interface in the Preferences dialog box, which can be found in the Edit menu.

IMPORTANT

2

You can check the resolution of the image in the

field Resolution in the Image Size box.You can also access the Image Size box by pressing the key

combination Alt + Ctrl + I.

1

You heck the olutio f the ima in the

15

001

Learning Image processing with Photoshop CS6 with 100 practical exercises

fore you continue, deselect Resample Image by clicking on its

checkbox. 3 This is how you can avoid the loss of the image’s

quality.

4. Now you can change the resolution value. In this example,

and always thinking that our purpose is to print the image on

paper, double-click the Resolution field and enter the value

150. 4

5. You have decreased the dimensions of the image proportion-

ally while achieving a higher resolution. Be aware of the fact

that you could still gain a little more resolution if the target of

the photograph was a press printer, any further action would

reduce the size of the image while mantaining its quality.

Click OK to accept the process.

6. Apparently there hasn’t been any changes made to the image,

so you should print it to check the quality. If it is okay, you

may return to the Image Size dialog box and keep the Resa-

mple Image check box enabled: the loss of the quality will be

visible on the photograph as you apply all changes.

The Resample Image option is enabled by

default. This can cause the loss of definition

of the image or it can be blurred or

pixelated while changing its resolution.

The appropriate value to print a photo on an

inkjet color printer is 150 pixels per inch.

By activating the Resample

Image option you can choose

from different resampling

methods according to the

destination of the image.

The Scanned images have a higher resolution than those you took with a digital camera, so if you want to resize them, you have to keep the Resample Image option enabled.

IMPORTANT

3

The appropriate value to print a photo on an

By

Ima

fro

met

des

4

5

16

Tilting and rotating an image

THE IMAGE ROTATION COMMAND, which can be found in the

Image menu, can quickly change the orientation of an image or

apply a specific degree of inclination. If you want to rotate the en-

tire image a half turn or quarter turn, use the options 180° or 90°

to the left or to the right. In order to apply a specific tilt angle it is

necessary to use the Arbitrary option.

1. In this exercise you will learn how to rotate and tilt an im-

age with Photoshop. This is a simple command, which can

be found in the Image menu. To begin, open the image you

would like to rotate in the program. (If you like, you can use

the sample image 002.jpg.)

2. Rotate the image 90° clockwise. To do this, open the Image

menu, then click on the Image Rotation option and choose the

90° CW command. 1

3. If you work with the sample image, you can see that its orien-

tation has now changed 90° to the right. Depending on the

orientation of the image you use, you may need to use the 90°

CCW command to rotate it 90° to the left. Now try to use the

180° command, which is also included in the submenu Image

Rotation in the Image menu. 2

The option included in

the Image Rotation

command in the

menu Image works

in individual layers,

a selection of layers,

paths, or selected

borders.

12

3

17

Learning Image processing with Photoshop CS6 with 100 practical exercises

0024. Now, the image is facing left. 3 To display the image in its

correct orientation again, open the Image menu, go to Image

Rotation and click on the 90° CW command.

5. Now let’s see how to apply a particular pitch to an image.

Open the Image menu, click on the Image Rotation option

and select Arbitrary. 4

6. This opens the Rotate Canvas dialog box, which you will use

to set the angle of inclination you want to apply to the image

and apply it to the left or right. In the field Angle you need

to enter a value between 0 and 359.99. For example, type the

value 45 and click on the °CCW option. 5

7. Thus, after accepting the command, the image is inclined 45

degrees to the left. Then press OK. 6

Note that if you want to rotate or tilt specific parts or layers of

the image, you should use the Rotate option, which can be found

in the Edit menu and then by clicking on Transform in the sub-

menu. Further, you can use the angled drawing tools, which ap-

pear on the element when selecting it, with the tool Free Trans-

form, which is also included in the Edition menu. 7 In addition,

to gently rotate the canvas and to get a non-destructive view from

any angle, you can use the Rotate View tool, which can be found

under Hand in the Tools panel. (This feature requires you to en-

able drawing OpenGL in the Photoshop preferences).

The options Flip Canvas Horizontal and Flip Canvas Vertical are used to flip an image horizontally or vertically along an axis.

You can restore the original appearance of the image from the

History panel, which can be displayed in the Windows menu, or

by closing the file without saving the changes.

In order to transform an image freely, you must convert

Background layer to Layer 0 prior to moving any layer, which is

an option in the context menu of the layer in the Layers panel.

IMPORTANT

4

5

67

18

Converting a picture into a poster

THE CHANGE IN SIZE OF AN IMAGE is directly related to its loss

of quality, more specifically, when we increase the size of an im-

age, the quality is reduced. Whereas if you reduce the size of an

image, its quality is not affected much, but when you increase the

size significantly, an image can become out of focus, blurred, or

pixelated. Photoshop can convert normal images into printable

poster sizes without losing even one pixel of the image quality.

1. To begin this exercise, open the image you want to enlarge

to poster size, go to the Image menu and click on the Image

Size option.

2. In a previous exercise you already had the opportunity to

check if the picture has the correct image dimensions and

resolution. Enable the Resample Image option. 1

3. Then, open the field under the Resample Image option,

which by default displays the Bicubic Automatic resampling

method, and choose Bicubic Smoother (best for enlarge-

ment). 2

Remember that the automatic adjustment of the image size in

proportion to the set resolution depends on the activation of the

Resample Image option.

Photoshop uses six interpolation methods to resample images: Nearest Neighbor to preserve hard edges and to produce smaller files, Bilinear to produce medium-quality files, Bicubic to achieve smoother tonal gradations, Bicubic Smoother, which is ideal for enlargements of images, Bicubic Sharper to reduce the size of the image by improving its focus and, Automatic Bicubic which is the selected option by default.

IMPORTANT

1

2

19

Learning Image processing with Photoshop CS6 with 100 practical exercises

0034. Then, in the Width field of the Document Size change the

unit Centimeters (or the unit you are using right now) to Per-

cent. 3

5. The reason for this change is that if you increase the image

size by a percentage, then there is absolutely no loss of qual-

ity, whereas you increase the size values for width and height,

this will cause the already mentioned effects of blur and fade.

Therefore, type in the Width field the value of 110 and accept

the changes. 4

6. At this point you should repeat this process about ten times

according to the initial image size and the poster size you

wish to obtain. To do this, you have two options: either re-

peat the steps mentioned above as many times as you wish or

create an action, which with just one button automatically

resizes the image. (If you want to create an action, see the

exercise in this manual on how to do it.) After changing the

size of the image, which previously was a simple picture and

now is a poster size, the image now has only a negligible loss

of quality. 5

Make sure that the Constraint

Proportions option is enable

so that the change also applies

proportionally in the field Height.

In the Status Bar of the image

you can check the display zoom

ratio applied to the image. Use

the View menu option to see

the image in full size or change

manually the value of that

percentage.

3

4

5

20

Using the Crop Tool

It is possible to change the orientation of the crop box by clicking the curved arrow icon in the dimensions fields.

CUTTING A PICTURE IS NOT THE SAME as reducing its size,

since in the second case the file dimensions are modified without

affecting the content and in the first case the areas of the image

are discarded. In Photoshop, there are different methods to crop

images: defining the content manually with the Crop Tool, indi-

cating the crop size and, form automatically.

1. You can use the sample image 004.jpg or any other image you

want to crop. After opening the image in Photoshop, select

the Crop Tool, which is the fifth tool on the Tools panel. 1

2. In Photoshop CS6, this tool has been noticeably improved:

now, when you click on the image it shows you a tag with

the actual size of the crop area and a practical guide for easier

operation. When you have decided which part of the image

you want to crop, use the drawing tool in the corners and on

the sides of the grid to frame the crop area. 2

3. In the Options Bar in the Crop Tool you can choose be-

tween different types of cuts. Original Ratio is enabled by

default. Pull down this menu and have a look at the available

options. 3

Notice that you can find the name of the layer you are working

on while using the crop mode in the Layers panel.

IMPORTANT

12 3

21

Learning Image processing with Photoshop CS6 with 100 practical exercises

0044. You can choose between different sizes of the predetermined

cut or choose your own size by using Save Preset, change the

size and resolution, and rotate the crop box. Keep Original

Ratio selected and click on the icon that shows a check mark

in the Options Bar and see the crop. 4

5. Taking advantage of the fact that we have not saved the

changes yet, you can reestablish the initial appearance of the

image. Open the Edit menu, and choose Step Backward. 5

6.

15 cm. Enter the values 10 cm and 15 cm in the fields, where

you can customize the size in the Options Bar, 6 and move

the image to the center of the crop area.

7. Before cutting the image, open the field View in the Op-

tions Bar of the Crop Tool in order to check which different

display options are available and enabled such as the Grid

option. 7

8. Depending on the image and type of cut you want to obtain,

one display mode can be more useful than the other. To con-

tinue with the cutting, click on the check mark in the Op-

tions Bar. If you are satisfied with the result, save the image.

You can also accept

the cut of the image

by pressing the

Return button.

You lso t

4

You can also use the Crop Tool to straighten images while cutting. To do this, select the Straighten option in the Options Bar of the tool and draw a straight line on the image to straighten it automatically.

IMPORTANT

56

7

You can

reestablish

the original

appearance of

the crop box by

clicking on the

icon that shows

a curved arrow in

the options bar of

the Crop Tool.