WHAT IS A MEGAPIXEL?

HWM (Singapore) - - Trends -

First, let’s look at what a megapixel ac­tu­ally is. Ev­ery im­age you see on a dig­i­tal pho­to­graph is made up of tiny dots, each one called a pixel. A megapixel is a term for one mil­lion of these pix­els, and megapixel is used to de­scribe the res­o­lu­tion of a dig­i­tal im­age, as well as the res­o­lu­tion of a dig­i­tal im­age sen­sor.

For ex­am­ple, when a JPEG im­age has a res­o­lu­tion of 4000 x 3000, it means that the im­age is made up of 4000 col­umns by 3000 rows of pix­els. It has a to­tal of 12,000,000 (4000 x 3000) pix­els, and since that’s a rather large num­ber to say, we shorten it by de­scrib­ing it as a 12MP (12,000,000 di­vided by a mil­lion) pic­ture.

Megapixel is also used to de­scribe the to­tal num­ber of pix­els on an im­age sen­sor. To create a 12MP im­age, an im­age sen­sor has at least 12 mil­lion pix­els, or pho­to­sites, on it. Each pho­to­site cap­tures light as it passes through the cam­era’s lens and hits the sen­sor, and trans­lates that into dig­i­tal in­for­ma­tion which is ren­dered into

an imagH by thH camHra’s imagH prRcHssRr.

ThH tR­tal num­bHr Rf Hf­fHc­tivH pixHls is dif­fer­ent from the to­tal num­ber of pix­els on a sen­sor. An im­age sHn­sRr can’t usH HvHry pixHl Rn it fRr the sim­ple rea­son that a sen­sor is rHc­t­an­gu­lar anG lHn­sHs arH rRunG. SR thHrH arH al­ways pixHls fall­ing Rut­siGH Rf thH lHns’ cRvHragH, anG thH Hf­fHc­tivH pixHls arH thH ac­tual num­bHr Rf pixHls which rH­main tR cap­turH thH light.

The num­ber of ef­fec­tive pix­els is the num­ber of pix­els which fall within a lens’ area of cov­er­age.

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