Brightness refers to the overall lightness or darkness of an image. Increasing brightness makes the image lighter; decreasing it makes the image darker.
Why Adjust Brightness?
Improve visibility of details.
Correct under‑exposed or over‑exposed photographs.
Match the image to the surrounding design.
Common Software Used in IGCSE
Software
Platform
Typical Use
Microsoft Paint
Windows
Basic brightness adjustment via “Select → Adjust → Brightness/Contrast”.
Adobe Photoshop
Windows / macOS
Precise control using “Image → Adjustments → Brightness/Contrast”.
GIMP
Windows / macOS / Linux
Free alternative; “Colors → Brightness‑Contrast”.
Step‑by‑Step Procedure (Using Paint)
Open the image file: File → Open.
Select the whole image: Ctrl+A or Select → Select all.
Open the brightness tool: Select → Adjust → Brightness/Contrast.
Move the Brightness slider:
Slide right to increase brightness.
Slide left to decrease brightness.
Observe the preview window. When satisfied, click OK.
Save the edited image: File → Save As (choose a new file name to keep the original).
Step‑by‑Step Procedure (Using Photoshop)
Open the image: File → Open.
Ensure the layer is unlocked (double‑click the Background layer if necessary).
Choose Image → Adjustments → Brightness/Contrast.
Adjust the Brightness slider:
Positive values brighten the image.
Negative values darken the image.
Optionally adjust Contrast to maintain detail.
Click OK and save the file.
Key Points to Remember
Always work on a copy of the original image.
Small adjustments (±10 to ±20) often give the best results.
Check the image on different monitors or printouts, as brightness can appear differently.
Combine brightness changes with contrast adjustments for a balanced look.
Practice Activity
Download the sample image “sample‑photo.jpg” (provided by the teacher).
Adjust the brightness in three ways:
Make it noticeably brighter.
Make it noticeably darker.
Apply a subtle increase of +15.
Save each version with a distinct file name.
Compare the three versions and note which adjustments improve visibility of details.
Common Errors and How to Fix Them
Error
Cause
Solution
Image becomes washed out
Brightness increased too much without adjusting contrast.
Reduce brightness slightly and increase contrast.
Loss of detail in shadows
Brightness decreased excessively.
Raise brightness a little and consider using “Shadows/Highlights” if available.
Color shift
Software applies automatic color correction.
Disable any “Auto‑adjust” options and adjust manually.
Assessment Checklist
Can you open an image in the chosen software?
Can you locate the brightness adjustment tool?
Can you increase and decrease brightness and observe the effect?
Can you save the edited image without overwriting the original?
Can you explain why a small adjustment is often preferable?
Suggested diagram: Screenshot of the Brightness/Contrast dialog box in Photoshop, showing the slider positions for “Increase”, “Decrease”, and “Neutral”.
Summary
Adjusting brightness is a fundamental skill for improving image quality. By following a systematic procedure, using the appropriate software tools, and checking the results, students can ensure their images are clear, well‑balanced, and suitable for any ICT project.