Turn that noise down!

When you’ve pushed your cam­era too far, you get noise in your shots – but Light­room has a host of tools to help you get rid of it

Digital Camera World - - FUNDAMENTALS -

What is noise? It’s those splotchy un­even tones and ran­dom colours that ruin your im­age qual­ity. Noise is the rea­son you avoid push­ing your ISO. You even bought a tri­pod to get steady shots at longer shut­ter speeds, just to avoid bump­ing it up.

While grain in film looks pleas­ing and or­ganic, dig­i­tal noise is far less pleas­ing. Of­ten sit­u­a­tions re­quire us to use less than op­ti­mum set­tings in or­der to get the shot. Cam­era tech­nol­ogy has much im­proved, but hav­ing to push the im­age sen­sor still in­tro­duces noise. Noise dis­plays in a few ways. Chroma noise dis­plays as both ran­dom-coloured pix­els in ar­eas of even colour and as ar­eas of colour dif­fer­ences when the hues should be uni­form.

Lu­mi­nance noise is based on vari­ances in bright­ness. It shows where ar­eas should be of even tone, but aren’t. Fix­ing lu­mi­nance noise is done by blur­ring, so care needs to be taken.

Pat­tern noise typ­i­cally ex­hibits as a criss-cross based on the sen­sor. It’s more vis­i­ble if you push up the ex­po­sure on very high ISO shots. Light­room doesn’t deal with this – but then, few ed­i­tors do.

With Amount at 0, the splotch­i­ness in the shot is vis­i­ble. Us­ing the win­dow in De­tail, you can see the ef­fect as you make changes. At the de­fault of 25, the chroma noise looks rea­son­ably con­trolled. We’re not see­ing much in the way of noise arte­facts. By set­ting Amount to 100, you can see the full ef­fect of blur­ring. While there are still edges, they’re quite soft, so it’s not ideal. By re­duc­ing Amount to 0, the noise in the im­age be­comes ap­par­ent. The blue ar­eas are now mixed with pur­ples and greens.

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