Midterm Exam 1 Review Spring 2004: Check your luminance
(Return to Sp2004 Midterm 1 Review)
Questions, answers, comments on answers, comments on questions?
This is Paula Verden.
My question is are we suppose to use part of the greyscale reciepe in our new recipe for luminance.
| Yes – use the same calculation for luminance as what's provided in this function. But your function will input red, green, and blue, like this: def checkLuminance(red, green, blue):. Mark Guzdial |
Amelia Cipolla
How is this done without the input of a picture? what do you do if you cant say
for p in getPixels(picture)??
what is your "for" statement?
this is what i have
def checkLuminance(picture, red, green, blue):
for p in getPixels(picture):
newRed=getRed(p)*0.299
newGreen=getGreen(p)*0.587
newBlue=getBlue(p)0.114
luminance=newRed+newGreen+newBlue
setColor=(p, makeColor(luminance,luminance,luminance)
if luminance < 10:
print "That's going to be awfully dark"
if luminance >49 adn < 201:
print "Looks like a good range"
if luminance >250:
print "That's going to be nearly white"
So you are saying there is no picture input, no reference to pixels. so is this what you want?--
def checkLuminance(red, green, blue):
redvalue=red*0.299
greenvalue=green*0.587
bluevalue=blue*0.114
luminance=redvalue+greenvalue+bluevalue
if luminance < 10:
print "That's going to be awfully dark"
if luminance >49 adn < 201:
print "Looks like a good range"
if luminance >250:
print "That's going to be nearly white"
| You don't need to have the input of a picture because all you're doing is looking at a red value, a green value, and a blue value. Write it as a function that could be used outside of the context of a picture. Say, for instance, that somebody else was working on a program to change a picture to greyscale. They don't want to worry about the luminace, though. They want you to write a function that will do that for them. They'll call it every time they look at a pixel in their picture. All they'll give you is the RGB value and they want the luminance back (Plus a little warning about the visibility). Adam Wilson |
Catherine Covington Is this code clear or am I missing something?
def checkLuminance(red, green, blue):
for px in getPixels(picture):
newRed = getRed(px) 0.299
newGreen = getGreen(px) 0.587
newBlue = getBlue(px) 0.114
luminance = newRed+newGreen+newBlue
setColor(px,makeColor(luminance,luminance,luminance))
if(luminance <10):
print "That's going to be awfully dark"
if(luminance >50 and luminance <201):
print "Looks like a good range"
if(luminance >250):
print "That's going to be nearly white"
| It's clear, Catherine, but you're trying to do too much. Where does the value of 'picture' come from? Look at Amelia's second code example above. Colin Potts |
| How do you think the program would be different if the Amelia's second code example read luminance=int(redvalue+greenvalue+bluevalue)? Mark Guzdial |
def checkLuminance(picture):
for px in getPixels(picture):
newRed = getRed(px)*0.299
newGreen = getGreen(px)*0.587
newBlue = getBlue(px)* 0.114
luminance = newRed+newGreen+newBlue
print luminance
if luminance<10:
print "That's going to be awfully dark"
if 50250:
print "That's going to be nearly white"
Margaret McIntosh is this right?
| You're on the right track, but your program needs to take color values as inputs, not a picture... |
Amy Howard
def checkLuminance(red, green, blue):
newRed = red*.299
newGreen = green * .587
newBlue = blue*.114
luminance = newRed + newGreen + newBlue
if luminance < 10:
print "That's going to be awfully dark"
if 50 < luminance < 200:
print "Looks like a good range"
if luminance > 250:
print "That's going to be nearly white"
Amelia Cipolla
Is it wrong that in my second example I do not refer to any pixels??? (like getRed(p))???
| You might need to check the luminance of a color for other reasons than probing pixels in a picture. Suppose checkLuminance was part of an interior design application that let a user choose wall or carpet colors. This function might be a useful sanity check for color values that a user might regret. (Okay, this example may not be good design aesthetics, but you get the idea...) Colin Potts |
Lindsey Richardson
Am I on the right track?
def checkLuminance(red, green, blue):
redValue = red * 0.299
greenValue = green * 0.587
blueValue = blue 0.114
luminance = redValue + greenValue + blueValue
if(luminance < 10):
print "That's going to be awfully dark."
if(luminance >= 50 and luminance <=200):
print "Looks like a good range."
if(luminance >250):
print "That's going to be nearly white."
| That looks good, also check FAQ for how to format code on Coweb. |
When you have to say that between 50 and 200 "looks like a good range," are you supposed to say 50 = luminance = 200, or 50 luminance 200? In general, what makes the difference in when you include the numbers at each end or not?
daniel goers
def checkLuminance(R,G,B):
newRed = R 0.299
newGreen = G 0.587
newBlue = B 0.114
luminance = newRed+newGreen+newBlue
if luminance 10:
print "That's going to be awfully dark"
if luminance < 200 and luminance > 50:
print "Looks like a good range"
if luminance > 250:
print "That's going to be nearly white"
| Check the indentation and content of your first 'if' statement. Colin Potts |
I think I"ve got it right...I have:
def checkLuminance(red, green,blue):
redvalue=green*0.299
greenvalue=gree*0.587
bluevalue=blue*0.114
luminance=redvalue+greenvalue+bluevalue
if(luminance<10):
print "That's going to be awfully dark."
if(luminance>=50 and luminance<=200):
print "Looks like a good range"
if(luminance>250):
print "That's going to be nearly white"
I have a feeling my spacing is going to be incorrect, but it's correct in JES
Kyla LeCroy
| Spacing would be right here, too, if one would read and follow the directions on the FAQ...:-) Mark Guzdial |
I am little confused with the statement "between 50 and 200." Does this mean that 50 and 200 are included? Or, are they excluded? Also, would you write "50 < luminance < 200" or would you write "if luminance > 50 and luminance 200" ???
poof #2
| Lauren, this isn't really anything to worry about. If there is a is a problem like this on the midterm, it will be clear whether the numbers are inclusive or the numbers should not include the endpoints. Greg Leo |
Link to this Page
