The top three rows' high bits clue ATOMIC, TEENY-TINY, and LITTLEST.
The top three rows' low bits clue MICRO, KINDERGARTEN, and LILLIPUTIAN.
The bottom row clues ADOLESCENT, SLIM, and LIMITED.
Each of these words is a different length. Putting them in order by length and reading off the first letters gives SMALL TALK, which this puzzle certainly is!
The bottom left
In the bottom left corner, there is a set of gray pixels. Taking their RGB values and converting to Ascii gives the message
Crazylatesecond. (After that is a fully-white pixel, which I assume means "message finished".) This could mean ADOLESCENT, where "crazy" is a cryptic crossword style anagram indicator.
The bottom middle
The colors between the two white squares in the bottom row all seem to have "nice" values in hexadecimal. They are:
Colorhexa lists these as Silver, Lime green, Indigo, and Maroon; the initial letters here spell SLIM. (There's most likely another, more "official" source where these are all listed; my first thought was HTML color codes, but that wasn't it.)
The bottom right
The red and blue values are all multiples of 45 (well, usually), and the green values are all numbers from 1-7. Interpreting the red and blue values as flag semaphore, then sorting by the green values gives LIMITED - which is fitting, because in the E and D one of the values was set to 255 instead of 270 (since color codes are one byte each).
Top 3 rows, part 1R
Taking only the pixels with a large red component spells out "ATOMIC".
Top 3 rows, part 1G
Taking only the pixels with a large green component spells out TEENYTINY in Braille.
Top 3 rows, part 1B
Taking only the pixels with a large blue component spells out LITTLEST in Morse code.
Top three rows, part 2
Each of the "large components" is at least 230. Subtracting 230 from each component and reading off red, green, and blue separately gives us three new messages...
Top three rows, part 2R
Most of the pixels are zero. The ones that aren't count up from 1 to 23, skipping 4, 10, 13, and 17. Drawing lines between the pixels (picking up your pencil during a skip) gives:
and $10^-6$ is MICRO.
Top three rows, part 2G
The pixels in this section are divided into three blocks.
Converting letters to numbers spells out "MORE NICE THAN / LONG NOSE FISH / FIVE OVER HALF", which clue KINDER, GAR, and TEN. Therefore the answer is KINDERGARTEN.
Top three rows, part 2B
The nonzero pixels in this section make letter shapes.
Reading off the letters based on the numbers on them (repeating for repeated letters) gives LILLIPUTIAN.