(f) Exercise 6 - Basic Image Corrections

(f) Exercise 6 - Basic Image Corrections


Original Image

Final Corrected Image

Tasks:1) Copy the ‘Lesson 7’ folder from the server and place it on the desktop. (Remember to delete this folder when you have completed this exercise).


2) Start Photoshop CS4 and open the document ‘BadImage.jpg’


3) Rotate the image 90 degrees to orientate it correctly.


4) Display the Rulers. What is the keyboard shortcut ? Ctrl (apple key) R


5) Use ‘Photoshop->Preferences->Units and Rulers…’ to swap between cm and pixels for the ruler dimensions.


6) Display the Grid. What is the keyboard shortcut ? Ctrl (apple key) '


7) Use ‘Photoshop->Preferences->Guides, Grids, Slices and Count …’ to change the grid spacings.


8) Use the Measure tool to draw a line down the centre of the façade following the joins in the bricks. Record the following :-a) How long is the line in pixels and in cm ? 6cm, 708px(Hint: Use the info palette and the ‘Units & Rulers’ preference)b) What is the angle of the line ? 92.6


9) Rotate the image so the image is straight using ‘Image->Rotate->Arbitrary…’


10) Use the crop tool to crop out any background pixels added around the outside of the image - you will lose some of the image to do this.Note: You can use the arrow keys to nudge the selected area by one pixel at a time. Shift + Arrow key nudges by 10 pixels.


11) Open the Curves palette and adjust so the image has a full tonal range and good overall brightness (Gamma correction).What has happened to the histogram ? The avaliable tonal range has been spread across the entire spectrum in order to reach both ends of the spectrum to express pure blacks (shadows), greys, and pure whites (highlights) within the image. By stretching the tonal range of the image it creates gaps ( a 'comb' effect) along the histogram because of the limited tonal range of the original image.


12) Set the background colour to black.


13) Increase both the width and height of the image by 1cm using ‘Image->Image Size …’.


14) Undo the change in size.


15) Increase both the width and height of the image by 1cm using ‘Image->Canvas Size …’.


16) What is the difference between changing the image size vs. changing the canvas size ? When changing the 'image size' it physically resizes the image (changing the pixels/cm/inches). When changing the 'canvas size' the image quality remains the samehowever the size of the image is cropped to whatever size is requested.
17) Use the Clone stamp tool to remove the pole to the left of the tower. Turn OFF the ‘Align’ option, set the brush size to approx. 8 pixels, and ‘Alt + click’ in the sky to set the point to start copying from.


18) Use the Clone stamp tool to remove a window from the façade of the building.Turn ON the ‘Align’ option, set a soft brush with a diameter of 20pixels, and ‘Alt + click’ in the brickwork to set the point to start copying from.a) How does the behaviour change when the ‘Align’ option is turned off ? When the align option is turned ON you can reproduce the entire sample image area, however when it is turned OFF you can only repeat the area in which you have sampled.


19) Save the image as ‘MasterImage.tif’


20) Close the document.


21) Quit Photoshop.22) Delete the ‘Lesson 7 folder.


23) Shutdown the computer.