photoshop survival guide for psychologists

Hi there, I made this tutorial whilst postdocing in Bangor, UK. For the visual science researcher. ¬†How to make funky stimuli ūüôā

Here is the pdf.

The Photoshop Survival Guide for Psychologists    1

Essential areas in the Photoshop window that you need to become familiar with:    2

Tools (area 1 in the main window)    3

1. Rectangular marquee tool    3

1. Rectangular marquee tool    4

2. Lasso tool    4

3. Crop tool    5

4. Clone stamp tool    6

5. Eraser Tool    7

6. Blur Tool, Sharpen Tool, Smudge Tool    7

7. Colour choosing area    8

9. Magic wand tool    10

10. Paint tool    11

11. Gradient tool and Fill tool    12

12. Burn, Dodge and Sponge tools    13

13. Text tool    14

14. Shape tool    16

15. Pipette tool    17

16. Magnifier    17

Layers (area 2 in the main window)    18

Actions and History (area 2 in the main window)    20

Actions    20

History    22

Creating a new image    23

Problems    23




Essential areas in the Photoshop window that you need to become familiar with:




Useful shortcuts:

Ctrl n: New document

Ctrl c: Copy

Ctrl v: Paste


BUT I use a MAC!

Everything mentioned throughout this handout CAN be done using a MAC. However, some of the shortcuts will be different. My advise, experiment! Tricky also that the MAC only has one mouse button. NOTE that many of the PCs right click functions can be done by holding down the APPLE button and clicking.





Not sure what a particular button does on screen? Move the cursor over it and wait a few seconds. Text will appear, telling you what the button does.


E.g. Hover the mouse over the icon that looks like a can of paint.


Tools (area 1 in the main window)



HINT: Multiple tools are sometimes hidden within 1 button.

For some of the buttons on the toolbar, note that there is a small arrow pointing down and to the right in the bottom right hand corner. This indicates that there are other, similar, tools hidden ‘behind’ a button. To get access to them, click and hold down on one of these ‘multi-tool’ buttons:


E.g. Holding down on the Rectangular Marquee button, reveals other similar tools. Selecting one of these tools will allow you to use that tool, and this will change symbol on the toolbar to this tool too.


1. Rectangular marquee tool

2. Lasso tool


Used to select areas of your picture that you wish to copy, transform or delete

IMPORTANT: check out area 4 in the main window (4MW). Specifically, the “Feather” box, where you can specify how ‘hard’ the outline of the area of the picture you have selected. E.g.


Feather = 0 :             Feather = 1 :

Why is this useful?


Good for inserting images into other images (e.g. replacing one person’s head, with that of another person’s). A Feather of 1 would make the resulting image a bit more natural, and would require less ‘touch-up’ work later on.


Note also how the Feather = 0 image seems more DIY. Feather = 1 image is neater.



Feather = 5:

Why is this useful (Feather>1)?

Allows you to blend images together.




Find it hard to select the area that you want first time? No worries! Have a play with the CTRL, ALT and SHIFT buttons, and you’ll notice that your cursor changes shape:


Here, I’ve pressed the CTRL button, and a + symbol has appeared next to the lasso icon. Whilst hold down this the CTRL button, I can now select ADDITIONAL areas to add to my selection. In a similar fashion, when the ALT button is pressed, a minus symbol will appear, allowing you to DESELECT what you now select.

Check out the menu item ‘select’ for more advanced options.

Annoyed that the selection tool is not letting you select WHAT you want to select? Try using the CTRL whilst making your selection. Should allow you to minutely control the size of your selection. Also try the ALT and SHIFT buttons.


Try Select > Inverse, to invert your selection (i.e. select the exact opposite to what you have already selected).


3. Crop tool


Used to easily reduce or increase image size.


Use in a similar fashion to the selection tools (see tools 1 & 2 above). Select the area that you wish to keep. Press Enter, and the image will resize accordingly.





Also note that you can increase the image size using this method (hint, use the magnifier to make your image smaller than the window that contains it; then use the crop tool to select an area larger than the size of your actual image).




(n.b. I added a border to this image).







4. Clone stamp tool


Used to paint one area of your image with the contents of another area. Handy for retouching.



Here, I’ve replaced Dougal’s head with Father Ted’s. Notice that Ted’s head does not completely cover Dougal’s. The trick is to copy what is already in the image over the remains of Dougal’s head. By using the clone tool, we can dynamically copy pixel information from 1 area, and paste it in another area.


TASK: replace remains of Dougal’s head with the wallpaper.


Step 1. Select the area of the image that you want to clone. Hold down the ALT button and the cursor will change shape to a target (see the image below). Click whilst holding down alt.

Step 2. Left click on the area of the image that you wish to ‘paint’ with the area that you selected in Step 1 (image below the image below!). Photoshop displays a circle in the area where you are painting, and displays a cross in the area from where the ‘paint’ is coming from.


IMPORTANT INFO: Check out area 4MW. Play with the ‘Opacity’ and ‘Flow’ values. I advise using high values (~100%) for making BIG changes, and then progressively use smaller values for more subtle changes.

IMPORTANT INFO: In area 4ML, notice the Brush option. Click here to play with the size of your brush.

(Image 1) Using 100% values for Opacity and Flow:

(Image 2) Using <20% values for Opacity and Flow to ‘iron-out’ problems in the picture.


(bottom, result of 5 minutes dabbling; notice dodgy wallpaper above Ted’s head! Given time‚Ķ).





Powerful when used in conjunction with Layers. This tool can even be used ACROSS layers. Just define your selected area (step1) in one layer, and then select the layer you wish to copy pixels from.






5. Eraser Tool


Handy tool when used in conjunction with layers. Note also that Opacity and Flow (see area 4MW) can be adjusted with this function, allowing you to ‘partially’ delete an area. Good for merging one image into another.


If you have selected an area on the screen using the Lasso and square Marquee tools (Tools 1 & 2), pressing DELETE will erase what is selected.


6. Blur Tool, Sharpen Tool, Smudge Tool

(3 tools for 1 icon? Here’s how: link)


Used to manipulate the border between 2 parts of an image. Useful if things do not go as planned when copying and pasting (i.e. you did not use the correct feather value)


Going back to the image where we replaced Dougal’s head with Ted’s, notice that the right of Ted’s head seems wrong (it has been improperly copied and pasted, leading to that harsh vertical truncation to his head).


Note that for all these tools, you can adjust their strength in area 4MW.



Sharpen (produces the opposite effect, making this harsh edge stand out even more)






Smudge, does what its name suggests:




HINT: Use Smudge to rebuild the shape of Ted’s head, and then use the Stamp tool to fill the area with hair (i.e. to achieve a consistent texture across the head).



7. Colour choosing area

Set Foreground Colour

B: Default Foreground and Background colours

C: Switch Foreground and Background colours

D: Set Background Colour



The colour within A is the colour that will be painted to the screen when you use the paint tool (10MW) or other similar tools.


The colour within B will be used as the background colour of a new image. This colour also is used by other functions within Photoshop (e.g. Filter > Render > Clouds; when you use this function, having blue as the foreground colour, and red as the background colour will lead to the creation of blue and red clouds)


Clicking C swaps the background and foreground colour (VERY HANDY; I use this feature to store colours from a particular part of the image [see the pipette tool] so that I can later use that colour elsewhere.


How do I pick different colours?


Double click on A or D. The below window will pop up. Notice the multicoloured vertical bar in the centre of the screen. By dragging the small triangles (they are a quarter the way up this bar at the moment), you can change the colour within the large box on the left of this window.


Within the large box on the left you will notice a circle, in the top left corner. This circle highlights the colour that you have currently selected, and by moving it, you may change the currently selected colour.


8. Move tool


A very powerful tool, useful for:

Moving what is selected around the screen (strangely enough)

Transforming what you have selected (strangely enough!).


  1. Moving what is selected around the screen


  1. Select the area of the image you wish to move.
  2. Click the Move tool and then drag the area you selected to where you want it.



Note the white box that is left behind. The box is white, as my background colour was set to white (see the section: colour choosing area).



b) Transforming what you have selected (strangely enough!).


  1. Select the area of the image that you wish to transform in some way.
  2. Make sure that in area 4MW, that the box “show transform controls” is ticked.
  3. Transform the selected area:



Move the mouse over a corner one of the corners of the area selected. Click and drag that corner, and the area you have selected will change in size. To MAINTAIN the aspect ratio of the selection, hold down SHIFT whilst you drag the corner. To commit to the change, press enter.



Move the mouse within the vicinity of a corner of your selection, and it will change shape to a curved line with an arrow each end. Click and drag now, and the image will rotate. TRICK: Hold down SHIFT while you do this, and the selected area will rotate in 15 degree blocks. To commit to the change, press enter.


Other transformations

Check out Edit > Transform.

e.g. Flipping the image horizontally or vertically, Skewing, Distorting the image.


Help! I can’t get something to rotate (or do some other transform)!

Sometimes things just don’t work. If this is happening to you, try the more formal way of rotating your object: Edit > Transform > Rotate.
Still no luck? Try swearing loudly and shaking the monitor.


Handy way of selecting an area of an image that is of the same colour. Useful for removing an images background.


Note below, that the background is blue. Clicking within the background with the Magic wand tool will automatically select all LINKED areas of within that blue area that are similar to the area where you clicked.


Note below that part of Ted’s head has been included in this ‘magic selection’. I recommend now using the Lasso tool (see tool 2), to remove the parts of Ted’s head that have been inadvertently selected (holding down alt lets you do this).


Alternatively, when using the Magic Wand tool, change the tolerance of the wand within area 4MW. By reducing this value, you specify that you want a smaller window of tolerance.


Tolerance = 32            Tolerance = 18             Tolerence = 5.

. Paint tool


Used for freehand drawing.


Check out the toolbar (4MW), where you can specify your paint brush.


Clicking on the button next to Brush allows you to change the diameter of the brush and its hardness (hardness 100% means that a completely solid line is drawn, while <100% means that the line will be somewhat more transparent towards the outer ‘bristles’ of the brush).

Note that the brush’s colour, when painting within a window, is the same colour as specified as the foreground.


For more advanced options, check out “brushes”, located to the far right of area 4MW.



1. Gradient tool and Fill tool

(2 tools for 1 icon? Here’s how: link)


The gradient tool is used for creating:


To use this tool, click in the image (or selected area) and then drag the mouse. You will see a line form. When releasing the mouse, a colour gradient block will be created, such that the foreground colour is used for the start of the block, and the background colour is used for the end of the block (note that areas to the left of the line below will be the SAME colour as the foreground, and areas to the right of the line below will be the SAME colour as the background).




The fill tool will fill the entire image (or entire selection) with whatever colour you specified as the foreground.


12. Burn, Dodge and Sponge tools

(2 tools for 1 icon? Here’s how: link)


Allow you to subtlety adjust the intensity and colour of parts of your image. Check out Dougal’s left cheek in the images below (i.e. his cheek facing the right!).






































Dodge: lighten the image.

Burn: ‘darken’ the image (increase the intensity of the colour).

Sponge: remove colour from the image


You can adjust the strength of each tool within area 4MW (check out “Exposure”).

13. Text tool


Select the tool and click somewhere on your image. A blinking cursor will appear. Type and your text will appear on screen.

Notice that in area 4MW a number of fairly well known options become available to you. Notice the area above that says “Regular”. Within this option, you can change how the text appears on screen (bold, italic etc).


Also notice the T with the bendy double headed arrow beneath it on the far right of the image above. Clicking on this property brings up this window:



Here, you can specify all sorts of weird and wonderful text properties. I have told Photoshop here that I want my text to be arced, and by playing with the settings, I can specify just how arced I want my text.

Here is the result:







(note that I have used Filter > Render > Clouds to get this cloud background)


Note also that if you need to go back and change your text at a later date, all you need to do is select the text tool and then click on the text you want to edit (make sure that you have selected the layer that has the text on before you do this).

If you’re bored and fancy mucking around, check out the styles window, located above area 3MW. Click on a style, and that style will be applied to your text. E.g.




If you want more control over how you want your text to appear, double click where the arrow is pointing in the image below (area 2MW):









This window will pop up:

Have a play, this is slightly beyond what I wish to talk about in this tutorial!



Help! No text is appearing!

Your text will be the colour you specified as the foreground colour. No will see no text appear if your foreground colour is the same colour as that appearing behind the location where you are typing.


How on earth do I rotate my text on screen?

Check out the move tool (tool 8). This function works with text.


Note: I recommend rasterising text only if you are COMPLETELY happy with how it appears, or if you need to blend it in some cunning way with an image. Rasterising text can lead to problems if you later change the resolution or size of the image (e.g. if you are asked by a journal).

14. Shape tool




Click and hold the mouse button down on this tool, to bring up a range of shapes that may be drawn easily within photoshop. Check out area 4MW for options regarding the shapes you draw.



After you have made your shape, I recommend right clicking on the image of your shape within its layer (i.e. to the left, right click ON the actual image of the white arrow), within area 2MW. Then select “Rasterize Vector Mask”. This action will prevent you from editing your shape, but will allow you to combine it with other features of your image much more easily. DO THIS ALSO to force your shape to appear ‘normal’ (you’ll know what I mean if you experiment with shapes).





How do I draw a line with an arrow on the end?

Select the line tool (see above).


In the image above, note the black triangle next to the amoeba like squiggle, in the centre of the tool bar. Select it, and a toolbar appears, allowing you to specify that your line has arrowheads. Play with the settings here to change the size of the arrow head.


15. Pipette tool

Used to select a colour in your image, and use that colour as your foreground colour.


16. Magnifier

Very useful tool. I suggest you become familiar with these shortcuts:


Hold down alt when clicking to shrink your image when you click.


How down alt and use the scroll button on your mouse to rapidly expand and shrink the size of your image.


By clicking and dragging over an area when using this function you will create a selection area. When you release the mouse button, Photoshop will zoom the image so that the area you selected fills the original picture size.




Layers (area 2 in the main window)


Layers are a VITAL part of Photoshop.

When you paste an image into a blank image in Photoshop (how do I get images from the web into Photoshop?), you will notice that the Layers window, bottom right of the photoshop screen, will update to display a tiny copy of that image that you just pasted.










If you paste another image into the same picture, another tiny image will appear in the Layers window.


Each of these tiny images represents a layer within the Photoshop image.






Each layer is independent from each other, and what you do to 1 layer will typically not happen to other layers.


By selecting Layer 2 (the Superted Layer), I can modify the contents of this layer, within modifying Layer 1’s contents (the FatherTed layer). To select a layer, just click on the appropriate tiny image within the Layers window. Here, I have used the move tool to rotate and move Layer 2.





There are many ways of creating new layers. To the left, I have selected Ted’s head. By right clicking on the selection and clicking on “Layers via Cut”, I can remove the selected area and place it into a new layer.












Linking Layers

Want to apply the same transform to 2 layers simultaneously? Try linking the layers. To do this, select the layers you wish to link (use the CTRL whilst left clicking on each layer you wish to link). Then, right click on your layer and select LINK. Alternatively, select the layers you wish to link, and then click on the button which I have indicated with a arrow, in the image on the left (looks like a ‘play’ symbol). Select ‘Link Layer’ within this menu to link the layers.


Merging Layers

Follow the same steps as above. Select ‘Merge Layers’ to merge only the layers that you selected. Dangerously, it is very easy to merge all layers together here, by selecting “Merge Visible”.


Deleting Layers

As above.


Making layers semi transparent

Select the layer you want to make transparent. Adjust the ‘Opacity’ setting within the Layers window.



Create backups of your layers by duplicating them ALL THE TIME. Within the menu option to the left, click ‘Duplicate Layers’ to achieve this.


Note that Photoshop treats the ‘Background’ layer as special, making life hard sometimes (for more info‚Ķ)


Actions and History (area 2 in the main window)



Actions are used to AUTOMATE tasks in Photoshop. They make life EASY for you!


Actions essentially are Macros, and they can be recorded in the same way as in Word. Photoshop has quite a number of built in Actions which we can ignore.


What do those buttons mean?:

  1. Stop recording an action
  2. Start recording an action
  3. Play an Action
  4. Create a new Action
  5. Delete a Action
  6. LOTS of other options.


Steps to record a new action

TASK: Apply a red background to 100 images, stored in a folder somewhere.

  1. Create a new action. Give it a suitable name (e.g. red_backgrounds_eriser). Note that you can assign your macro a keyboard shortcut if you want! Brilliant!


  1. Click record.



  1. Perform the actions that you wish to have done on ONE of your images.


  1. Click stop.


  1. Either open all your images within photoshop (good if n<20 I guess) and apply macro (click run on each image) or select File > Automate > Batch (see left).



Please create MULTIPLE backups of all your images when you use this tool


At the end of step 3, I recommend that you close your image before proceeding to step 4. Photoshop will ask you some ‘save specific questions’. Automatically remembers your ‘save specific answers’! This will prevent you from having to deal with ‘save specific questions’ when you eventually run your action.


My Action almost works correctly! Can I edit a small part of it?






Note the triangles located to each of the actions in the image on the left. By clicking on an actions triangle, you open up all the individual steps that were recorded. By using delete, record and stop, you can manipulate these steps. You can even change the order that the steps are undertaken, by dragging one step to a new location.









Delete Actions once you have finished with them.


Be wary when assigning keyboard shortcuts to actions (especially if you do not follow the above tip!). Actions can perform low level UNALTERABLE changes to you images, and it would be very easy to accidentally apply an action to an image by pressing the wrong button.


Back you images up A LOT.



To undo a mistake:

Select Edit > Undo, to undo what you did last.

To undo many mistakes (!)

Select Edit > Step Backwards many times


Check out the history window (see area 3MW); this is hard to find- it is buried behind “Actions.¬†¬†¬†¬† Photoshop stores your previous actions as a descending list within the history window. To undo multiple actions, click one of the previous actions you made (click Paste in this example). All actions occurring after the selected action will be disappear!
















Click File > New and this window pops up:


Specify the size of your image if you are creating an image from scratch (don’t bother if you have a copied image you wish to get into Photoshop). This can be done in Pixels, cm etc.


Press OK.












Q: Why is my image in black and white!

Q: Why can I not use Layers?

A: In the window above, make sure that you have specified ‘color mode’ correctly. Typically, you want your image to be ‘RGB color’. But you DO NOT need to create a new image to change this setting. Select Image > Mode > ‘RGB color’ to change this preference.


Q: Why can I not save my image as a JPG/GIF(etc)

A: Use ‘Save as’ instead of ‘Save’ within the File menu.


Q: I am publishing a paper, but the journal is requesting my images to be 150dpi? Eh?

A:150dpi corresponds to the Resolution box in the above image. To change the value of an already created image, select Image > Image Size and you can change this value here. Note that if you have Rasterized text in your figure already, before making this change, your text will appear blockey. Shapes will be similarly affected.


Q: How do I make subtly change the colour/contrast/brightness of an image?

A: Check out Image > Adjustments. Try the ‘variations’ options at the bottom of this window (I tend not to use this though, and use the functions: ‘Brightness/Contrast’, ‘Color Balance’, ‘Hue/Saturation’)Random Stuff





Common Mistakes

  1. The tools don’t work!

a) Photoshop ‘locks’ the background layer, preventing you from manipulating that layer. BUT, this is particularly troublesome as Photoshop typically places pasted images automatically into the background layer. SOLUTION: Right Click on the text of “background layer” (right clicking else where gives you different options!), select “duplicate layer‚Ķ” and click ok within the window that pops up. I recommend hiding the background layer, by clicking on the ‘eye’ residing next to the “Background” text. Select the new layer to begin working on it.


b) Make sure that you are working on the correct layer (in the image above, the “Background” layer has been selected, as indicated by its blue surround).



  1. ALL the windows in my Photoshop window have disappeared!
    1. Press Tab. An annoying shortcut, that hides/shows Photoshop windows.


How do I get an image from the web into Photoshop?

When you Copy an image from the web, getting it into Photoshop is easy. Just select File > New and Press Enter (do not worry about the screen that pops up). Photoshop will automatically create a new image that is identically sized to the image that you copied from the web. Now, simply paste your image from the web into the new, correctly sized, image.

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