A blog about scientific and medical visualization and all that’s involved.

Archive for the ‘quiz/giveaway’ Category

An Interesting Video

Posted by Janet on September 16, 2009

See video in this link:

Any idea where it might be? Perhaps the fact that I’m posting it is giving away the answer.

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Pop Quiz Solutions

Posted by Janet on May 18, 2008

The winner of the pop quiz has been contacted by e-mail today. The answers I was looking for were 913.1 kilobytes for question 1 and 3.57 megabytes for question 2. I have accepted a few other reasonable responses as well. These numbers can either be calculated or looked up in Photoshop by entering the parameters.

Here is the most detailed (and correct) response I received. This reader was unfortunately not the winner, but he gets credit for showing the calculation:

1). Assume that there are 256 greyscale levels. This means that each dot
takes up log2(256) = 8 bits = 1 byte of storage space. At 100 dpi (where
dpi is a linear measure), the number of dots in one square inch is 100 x 100
= 10000 dots per square inch.

An 8.5″x11″ image occupies 93.5 square inches. The number of dots in this
space is therefore 93.5*10^4 = 9.35*10^5. At 1 byte per dot, this
corresponds to 9.35*10^5 bytes. Under the strict definition of 2^10 bytes
per kilobyte, this becomes approximately:

(9.35*10^5)/(2^10) = 913.09 kilobytes.

2). For a CMYK image, assume 8 bits each are allocated to the C,M,Y, and K
channels for a total of 32 bits = 4 bytes per dot. As calculated in (1), an
8.5″x11″ image has 9.35*10^5 dots total. This results in an image size of:

9.35*10^5*4 = 3740000 bytes

Under the convention that 2^20 bytes = 1 megabyte, this is:

3740000/(2^20) = 3.57 megabytes

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Pop Quiz Giveaway

Posted by Janet on May 15, 2008

Here is our first pop quiz giveaway. E-mail the correct answer of both questions below and how you came up with the answer to by 11:59pm this Saturday, May 17 and I will pick a random winner of a brand new ipod shuffle. You must provide the correct answer and describe your method of deriving it in order to win. Please do not post in the comments section unless you want everyone to see your answer.

1. What is the file size of a 8.5″ x 11″ grayscale image at 100dpi? Give answers in units of kilobytes.
2. Give the file size (in megabytes) of a 8.5″ x 11″ CMYK image at 100dpi.

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