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GIMP Practical (v2.0)

IntroductionIn this practical we will work through some of the relevant basic features of GIMP,

useful for bitmap image editing.

Software This practical is based on GIMP and the instructions were based on v 2.8.!

"although the# should be ver# similar on other versions$.

• GIMP "www.gimp.org$

Data%ll of the input data used in this practical can be downloaded from the &abraham

&ioinformatics web site

"http'((www.bioinformatics.babraham.ac.uk(training.html $.

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Exercise 1 –Brightness/Contrast and Cropping an Image)e are going to start b# creating a standard page la#out and importing an image

so that we can optimise brightness and contrast levels.

*pen GIMP and import the TI++ le called -)esternblot.tif/ from the 0ata(GIMP

practical folder using'

File > Open

%lter the view so that the image is 1oomed to !3 of its original si1e.

4ave the image as a working 56+ le so we have a back up of the raw image

before we start editing'

File > Save As

7ow we are going to check the brightness and contrast levels of the image. dit

the brightness and contrast manuall# using the sliders, then reset the brightness

and contrast and edit them using colour levels.

4traighten the western blot image as #ou see appropriate.

6rop the western blot image to an appropriate si1e and e9port the nal image as

a TI++ le using'

File > Export As

Exercise 2 –Adding and assigning a colour to Alpha

ChannelsIn the 0ata(GIMP practical folder there is a le called

-bioinformaticslogos:uare.png/, it is an image of the &abraham &ioinformatics

logo.

Import this image into GIMP and add an alpha channel. dit the alpha channel

settings so that the white background is transparent.

9port this image in an appropriate format to maintain the transparenc#.

Exercise –!seudo"colour #$erla%sIn the 0ata(GIMP practical folder there is a folder called -+I4; image practical/.

 This folder contains gra#scale images for red, green and blue channels.

Import all three images, making sure that the# are <G& colour mode, and then

reduce each image to the appropriate colour using levels.

2

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*nce all images are the correct colour, combine images into a single image and

ensure that the underl#ing la#ers are visible.

9port the overla# image in an appropriate format onto the desktop.

=

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&icence This manual is > 2!, 4imon %ndrews.

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