I know I've seen a word that describes a person who has a high perception of details (for example, seeing specific information in a log file), but I can't recall it now.
Percipient is a term with probably a more physical-sense orientated than grasp-the-situation orientated bias than perceptive. (Perhaps through lack of use.)
This may not answer your question, but if you consult the following web site
you may find at least a partial answer to your question, and that is: a person who is high in graphoria. That is a term coined by Johnson O'Connor of the Johnson O'Connor Research Foundation (jocrf in the hyperlink). Graphoria is one of many aptitudes which O'Connor identified and measured in his life's work of matching people with jobs for which they were more-or-less ideally suited by aptitudes.
Graphoria relates to the ability to do "number checking" tasks quickly and efficiently without a great deal of effort. People high in graphoria are detail oriented and are able to scan words, numbers, lists, and symbols and manipulate them in numerous ways with a good deal of accuracy. They make good speed readers. Interestingly, former President Kennedy was high in graphoria and was also a speed reader, or so I was told.
One reason (and there may be many others) why people who are high in graphoria are so good at "number checking" is because they can focus and refocus on many different details without losing their place. For example, when I am reading a book and taking notes at the same time, I have trouble refocusing on what I'm reading, once I've looked away to take notes. As you can guess, I'm very low in graphoria. My eyes just cannot switch between two sources of words, numbers, lists, and symbols quickly and efficiently. There is definitely some drag time in going from one source to the another. Consequently, I would make (and have been!) a terrible clerk.
What I lack in graphoria, however, I more than make up for in ideaphoria, which is an aptitude involving the rapid flow of ideas, which equips me for jobs that require that particular skill set. Teachers, advertisers, writers, public speakers, innovators, inventors, entrepreneurs, even lawyers benefit from being high in ideaphoria.
For your own edification, I recommend highly that you look into the Johnson O'Connor website if you are the least bit curious about what your particular aptitudes are and how to exploit the ones in which you measure high, and "work around" the ones in which you measure on the low side.
I understand this thread dates back more than a year, but for someone who, as I stumbled upon this page, is still seeking an answer, how about "detail-oriented"
Since the question seeks a noun, I would go for precisionist. As per the Free Dictionary:
One who values precision; a purist.
Observant paying close attention especially to details; quick to notice; showing quick and keen perception; alert and paying close attention.
Perceptive having the ability to understand and notice things that many people do not notice; having or showing keenness of perception, insight, understanding, or intuition.
I would say that being observant is generally a conscious or practiced behavior, while being perceptive is more of a natural quality. Others might disagree with me on that.
(It's not clear whether you are looking for a noun or an adjective.)
Perspicacious Of acute discernment; having keen insight; mentally perceptive; having or showing penetrating mental discernment; having or revealing keen insight and good judgment; acutely perceptive or discerning; clear-eyed, clear-sighted, discerning.
If you will allow hyphenated words, detail-oriented would seem to fit.
OP is asking for a noun, but actually I don't think there is any common "neutral" English term for a person with a flair for noticing details (i.e. - someone who is keenly observant, eagle-eyed).
In the vast majority of contexts, what we're interested in about such a person isn't so much that they notice the details - it's what they do about details that aren't what they expect or want to find. Normally, because they want something changed, in which case we might call them a...
perfectionist, pedant, stickler [for the rules], etc.
Note that most words in this general category (adjectives as well as nouns) usually have negative connotations as per the above. Probably for that reason, we tend to use more general terms such as attentive, meticulous, thorough, reliable when we want to imply positive connotations.
Someone who pays attention to details is called a person who pays attention to details.
As FF has pointed out already, there really isn't one word that means this in any context.
If you really wanted a single noun that would do the job
(and probably several others at the same time, a potential saving),
you could call them
or you could use an adjective, like the other answers suggest.
thorough, detailed, particular, strict, exact, precise, fussy, painstaking, perfectionist, scrupulous, fastidious. But I think meticulous is the best word for this. "Meticulous in detail". "Meticulous attention to detail".
A sharp-eyed secretary noticed the mistake in time.
To be sharp-eyed generally means someone who has very good eye sight and/or the ability to spot small but significant details.
A similar expression is eagle eye as mentioned by FumbleFingers.
an editor with an eagle eye