Have a deep view into what people are curious about.

🔗 Solar System/Mars 🔗 Solar System

The Mars monolith is a rectangular object (possibly a boulder) discovered on the surface of Mars. It is located near the bottom of a cliff, from which it likely fell. The Mars Reconnaissance Orbiter took pictures of it from orbit, roughly 180 miles (300 km) away.

Around the same time, the Phobos monolith made international news.

🔗 Biography 🔗 Medicine 🔗 Biography/science and academia 🔗 Medicine/Society and Medicine

Min Chiu Li (Chinese: 李敏求; pinyin: Lǐ Mǐnqiú; 1919–1980) was a Chinese-American oncologist and cancer researcher. Li was the first scientist to use chemotherapy to cure widely metastatic, malignant cancer.

🔗 Anthropology

🔗 Books 🔗 Poland

The Scottish Book (Polish: Księga Szkocka) was a thick notebook used by mathematicians of the Lwów School of Mathematics in Poland for jotting down problems meant to be solved. The notebook was named after the "Scottish Café" where it was kept.

Originally, the mathematicians who gathered at the cafe would write down the problems and equations directly on the cafe's marble table tops, but these would be erased at the end of each day, and so the record of the preceding discussions would be lost. The idea for the book was most likely originally suggested by Stefan Banach, or his wife, Łucja, who purchased a large notebook and left it with the proprietor of the cafe.

🔗 Mathematics

Ramanujan summation is a technique invented by the mathematician Srinivasa Ramanujan for assigning a value to divergent infinite series. Although the Ramanujan summation of a divergent series is not a sum in the traditional sense, it has properties which make it mathematically useful in the study of divergent infinite series, for which conventional summation is undefined.

🔗 Apple Inc. 🔗 Video games 🔗 Computing

The Apple Pippin is a defunct open multimedia technology platform, designed by Apple Computer, and marketed as PiPP!N. According to Apple, Pippin was directed at the home market as "an integral part of the consumer audiovisual, stereo, and television environment."

Pippin is based on the Apple Macintosh platform, including the classic Mac OS architecture. Apple built a demonstration device based on Pippin called "Pippin Power Player," and used it to demonstrate the platform at trade shows and to the media, in order to attract potential software developers and hardware manufacturers. Apple licensed the Pippin technology to third-party companies. Bandai Company Ltd. developed the ATMARK and @WORLD models, and focused them on the gaming and entertainment business in Japan and the United States. Katz Media developed the KMP 2000, and focused it on vertical markets throughout Europe and Canada.

🔗 California 🔗 Companies 🔗 Technology 🔗 Private Equity 🔗 California/San Francisco Bay Area

Y Combinator is an American seed accelerator launched in March 2005 and has been used to launch over 2,000 companies including Stripe, Airbnb, Cruise Automation, DoorDash, Coinbase, Instacart, and Dropbox. The combined valuation of the top YC companies was over $155 billion as of October, 2019.

🔗 Canada 🔗 Architecture 🔗 Canada/British Columbia 🔗 Canada/Vancouver

The Vancouver Special is an architectural style of residential houses developed in Metro Vancouver, Canada. The style was popular in the 1960s to 1980s due to ability to maximize floor space with relatively cheap construction costs.

🔗 Computing

The Canon Cat was a task-dedicated, desktop computer released by Canon Inc. in 1987 at a price of US$1,495. On the surface it was not unlike the dedicated word processors popular in the late 1970s to early 1980s, but it was far more powerful and incorporated many unique ideas for data manipulation.

🔗 Computer science

Floyd–Steinberg dithering is an image dithering algorithm first published in 1976 by Robert W. Floyd and Louis Steinberg. It is commonly used by image manipulation software, for example when an image is converted into GIF format that is restricted to a maximum of 256 colors.

The algorithm achieves dithering using error diffusion, meaning it pushes (adds) the residual quantization error of a pixel onto its neighboring pixels, to be dealt with later. It spreads the debt out according to the distribution (shown as a map of the neighboring pixels):

${\displaystyle {\begin{bmatrix}&&*&{\frac {\displaystyle 7}{\displaystyle 16}}&\ldots \\\ldots &{\frac {\displaystyle 3}{\displaystyle 16}}&{\frac {\displaystyle 5}{\displaystyle 16}}&{\frac {\displaystyle 1}{\displaystyle 16}}&\ldots \\\end{bmatrix}}}$

The pixel indicated with a star (*) indicates the pixel currently being scanned, and the blank pixels are the previously-scanned pixels. The algorithm scans the image from left to right, top to bottom, quantizing pixel values one by one. Each time the quantization error is transferred to the neighboring pixels, while not affecting the pixels that already have been quantized. Hence, if a number of pixels have been rounded downwards, it becomes more likely that the next pixel is rounded upwards, such that on average, the quantization error is close to zero.

The diffusion coefficients have the property that if the original pixel values are exactly halfway in between the nearest available colors, the dithered result is a checkerboard pattern. For example, 50% grey data could be dithered as a black-and-white checkerboard pattern. For optimal dithering, the counting of quantization errors should be in sufficient accuracy to prevent rounding errors from affecting the result.

In some implementations, the horizontal direction of scan alternates between lines; this is called "serpentine scanning" or boustrophedon transform dithering.

In the following pseudocode we can see the algorithm described above. This works for any approximately linear encoding of pixel values, such as 8-bit integers, 16-bit integers or real numbers in the range [0,1].

for each y from top to bottom do
    for each x from left to right do
        oldpixel := pixel[x][y]
        newpixel := find_closest_palette_color(oldpixel)
        pixel[x][y] := newpixel
        quant_error := oldpixel - newpixel
        pixel[x + 1][y    ] := pixel[x + 1][y    ] + quant_error × 7 / 16
        pixel[x - 1][y + 1] := pixel[x - 1][y + 1] + quant_error × 3 / 16
        pixel[x    ][y + 1] := pixel[x    ][y + 1] + quant_error × 5 / 16
        pixel[x + 1][y + 1] := pixel[x + 1][y + 1] + quant_error × 1 / 16

When converting 16 bit greyscale to 8 bit, find_closest_palette_color() may perform just a simple rounding, for example:

find_closest_palette_color(oldpixel) = round(oldpixel / 256)

The pseudocode can result in pixel values exceeding the valid values (such as greater than 1 in a [0,1] representation). Such values should ideally be clipped by the find_closest_palette_color() function, rather than clipping the intermediate values, since a subsequent error may bring the value back into range. However, if fixed-width integers are used, wrapping of intermediate values would cause inversion of black and white, and so should be avoided.