大约有 15,590 项符合查询结果（耗时：0.0074秒） [XML]
Converting RGB to grayscale/intensity
... coefficients are correct. .3,.6,.11 is the old NTSC standard, not sRGB/Rec709 (which is what the web and most computers use). And your 0.25,0.5,0.25 is not a reasonable tradeoff — B is only 7% of luminance, you're wrong by 347%. The coefficients for sRGB/r709 (after linearization): Rlin * 0.2126 ...
Date query with ISODate in mongodb doesn't seem to work
...ow:
db.foo.find({dt: {"$date": "2012-01-01T15:00:00.000Z"}})
you'll get error:
error: { "$err" : "invalid operator: $date", "code" : 10068 }
Try this:
db.mycollection.find({
"dt" : {"$gte": new Date("2013-10-01T00:00:00.000Z")}
})
or (following comments by @user3805045):
db.mycollectio...
Divide a number by 3 without using *, /, +, -, % operators
... just typed it in my js console, it doesn't work with a number higher than 709 (may be its just my system) Math.log(Math.pow(Math.exp(709),0.33333333333333333333)) and Math.log(Math.pow(Math.exp(709),Math.sin(Math.atan2(1,Math.sqrt(8)))))
– Shaheer
Aug 30 '12 a...
Why does GCC generate 15-20% faster code if I optimize for size instead of speed?
... 1.122s -
Intel Core i3-3217U gcc-4.6.4 0.709s 0.709s -
Intel Core i3-3217U gcc-4.7.3 0.708s 0.822s -O2
Intel Core i3-3217U gcc-4.8.1 0.708s 0.944s -O2
Intel Core i7-4770K g...
“Diff” an image using ImageMagick
... which are mostly grayscale:
convert '(' file1.png -flatten -grayscale Rec709Luminance ')' \
'(' file2.png -flatten -grayscale Rec709Luminance ')' \
'(' -clone 0-1 -compose darken -composite ')' \
-channel RGB -combine diff.png
The idea is follows: convert both file1.png a...
How to check if hex color is “too black”?
...act blue
var luma = 0.2126 * r + 0.7152 * g + 0.0722 * b; // per ITU-R BT.709
if (luma < 40) {
// pick a different colour
}
EDIT
Since May 2014 tinycolor now has a getBrightness() function, albeit using the CCIR601 weighting factors instead of the ITU-R ones above.
EDIT
The resulting l...
Maximum number of records in a MySQL database table
...est value is 4,294,967,295
unsigned bigint largest value is 18,446,744,073,709,551,615
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Removing pip's cache?
... I have pip 20.1.1 but when I try pip cache purge I get next error: ERROR: No matching packages but I installed a lot of different packages already
– Mikhail_Sam
Jun 16 at 10:59
...
What is the difference between “int” and “uint” / “long” and “ulong”?
...
long: -9223372036854775808 to 9223372036854775807
ulong: 0 to 18446744073709551615
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Does Java have a complete enum for HTTP response codes?
...AUTHORIZED //401
javax.servlet.http.HttpServletResponse.SC_INTERNAL_SERVER_ERROR //500
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