Exercise 4 – Bit Depth and Colour Modes

How big is an A4 page in cm ?21cm x 29.7cm
Open the file ‘Img 1 – Ex 4 - Granger-Rainbow.tif’ in Photoshop :-
Select ‘Image -> Image Size …’ and ‘Image -> Mode’ and answer the following questions :–
Image size in cm: 29.63cm x 20.32 cm
Pixel Dimension: 3500 x 2400
Image size in megapixels: 8.4
Resolution of the image(ppi): 300 ppi
Image size in megabytes: 24M
Colour Mode: RGB
Bit depth: 8bpc – 24 bits
Hint: Use the Status line to display the image size – use the number on the left.

Use the ‘Image -> Mode’ menu to select the following modes / bit depths and fill in the table for each case listed.

Colour Mode
RGB
RGB
CMYK
Greyscale
Indexed Colour – 256 colours
Bitmap
Bit Depth per channel
8
16
8
8
N/A
1
Total Bit depth
24
48
32
8
N/A
1
No. of available colours
256
2.8x10^14
4.3 billion
256
-
2

Image Size (Mb)

24
48
32
8
-
1