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Converting RGB to grayscale/intensity
... Blin = B^gamma
where gamma is 2.2 for many PCs.
The usual R G B are sometimes written as R' G' B' (R' = Rlin ^ (1/gamma))
(purists tongue-click) but here I'll drop the '.
Brightness on a CRT display is proportional to RGBlin = RGB ^ gamma,
so 50% gray on a CRT is quite dark: .5 ^ 2.2 = 22% of ma...
REST API 404: Bad URI, or Missing Resource?
...to hide the HTTP communication related code and I used this helper all the time when I called my rest APIs from my code.
BUT I needed to write confusing extra code just because HTTP 404 had two different functions:
the real HTTP 404 when the rest API is not available in the given url, it is throw...
How to declare global variables in Android?
...ing disk, hitting network, anything blocking, etc) will be performed every time Application is instantiated! You may think, well, this is only once for the process and I'll have to pay the cost anyways, right? For instance, as Dianne Hackborn mentions below, it is entirely possible for your process...
Find out a Git branch creator
... Should this work on Windows? I got "Input file specified two times."
– Steve Chambers
Mar 25 '15 at 11:32
...
Which UUID version to use?
...on 1: This generates a unique ID based on a network card MAC address and a timer. These IDs are easy to predict (given one, I might be able to guess another one) and can be traced back to your network card. It's not recommended to create these.
Version 4: These are generated from random (or pseudo-r...
What's the best way to put a c-struct in an NSArray?
...ts copy of the structure is destroyed. If you've used getValue: in the meantime, you're fine. See the "Using Values" section of "Number and Value Programming Topics": developer.apple.com/library/ios/documentation/Cocoa/Conceptual/…
– Justin Spahr-Summers
Dec ...
How to check if a string is a valid JSON string in JavaScript without using Try/Catch
...ing that isn't JSON})
I also prefer to return the parsed JSON at the same time, so the calling code doesn't have to call JSON.parse(jsonString) a second time.
This seems to work well for my needs:
function tryParseJSON (jsonString){
try {
var o = JSON.parse(jsonString);
// Ha...
Amazon S3 boto - how to create a folder?
...creating keys.
You can see my below code i was creating a folder with utc_time as name.
Do remember ends the key with '/' like below, this indicates it's a key:
Key='folder1/' + utc_time + '/'
client = boto3.client('s3')
utc_timestamp = time.time()
def lambda_handler(event, context):
UTC_...
String to Dictionary in Python
So I've spent way to much time on this, and it seems to me like it should be a simple fix. I'm trying to use Facebook's Authentication to register users on my site, and I'm trying to do it server side. I've gotten to the point where I get my access token, and when I go to:
...
How can I select random files from a directory in bash?
...andf[@]}" if needed.
This one will possibly output the same file several times, and N needs to be known in advance. Here I chose N=42.
a=( * )
randf=( "${a[RANDOM%${#a[@]}]"{1..42}"}" )
This feature is not very well documented.
If N is not known in advance, but you really liked the previous pos...