What is RAW photo and how to work with it | Articles | Photo, video, optics

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Your cam­era sees more than it shows. In order to share with you a dig­i­tal copy of the image, it encodes the infor­ma­tion received on the matrix into a cer­tain for­mat. If this is JPEG — the ubiq­ui­tous image for­mat­ting stan­dard — then some infor­ma­tion is lost: the cam­era auto­mat­i­cal­ly con­verts pho­tos in a rea­son­able time and with avail­able resources (the elec­tron­ic “brains” of your cam­era are obvi­ous­ly infe­ri­or to the “stuff­ing” of a desk­top com­put­er).

As a result, the mem­o­ry card saves not what got on the matrix, but how the cam­era processed it. It turns out a fin­ished dish with its own advan­tages, but devoid of flex­i­bil­i­ty.

If you want to exper­i­ment with the “ingre­di­ents”, you need to take a step back and set up the cam­era so that instead of a for­mat­ted shot, it gives you the most com­plete reflec­tion of what was cap­tured by the matrix. This is how pho­tos are obtained in RAW for­mat, about the pros, cons and prin­ci­ples of work­ing with which we will talk in this arti­cle.

How a “raw” photo works

Benefits of RAW

The trans­for­ma­tion of a RAW file to JPEG takes place in sev­er­al stages, each of which affects the image in its own way. First comes the demo­li­tion. In order to under­stand how this process works, let’s first under­stand how dig­i­tal cam­eras gen­er­al­ly acquire images.

The cam­era matrix con­sists of mil­lions of pix­el cells. When you press the cam­er­a’s shut­ter but­ton, each of these cells begins to absorb light. Then the light in each cell is count­ed. To make images in col­or, a fil­ter (usu­al­ly three of them: red, blue and green) is super­im­posed on top of each light col­lec­tor, allow­ing only a cer­tain col­or to pass through.

The most com­mon matrix col­or fil­ter of this kind is the Bay­er matrix, which con­sists of alter­nat­ing rows of red-green and green-blue fil­ters.

Dema­triza­tion is to inter­po­late (i.e. find the miss­ing val­ues) of the col­or com­po­nents with the orig­i­nal image passed through the Bay­er matrix so that each cell is rep­re­sent­ed not by one col­or num­ber, but by three that make up the usu­al col­or rep­re­sen­ta­tion for­mat, for exam­ple, RGB.

This is a resource-inten­sive process, so the cam­era inevitably goes for sim­pli­fi­ca­tions dur­ing RAW to JPEG con­ver­sions. If you save the image in RAW, you can do the dema­triza­tion on your com­put­er your­self.

This is what demo­li­tion looks like. Source: hisour.com

Anoth­er fea­ture of RAW is that it retains the orig­i­nal bit depth of the image. If you remove the orig­i­nal data in JPEG for­mat from the matrix, you get 8 bits per col­or chan­nel. Accord­ing­ly, the dynam­ic range (chiaroscuro inter­val between absolute­ly black and absolute­ly white) of the frame will be lim­it­ed to 28=256 shades of red, blue and green in the RGB mod­el.

In RAW, the bit depth is high­er — 10, 12, 14 or 16 bits per chan­nel. These bits of RAW files have addi­tion­al data that will allow you to expand the dynam­ic range and get out of it those details that are lost in JPEG.

RAW uses loss­less com­pres­sion, unlike JPEG com­pres­sion, which pro­duces com­pres­sion arti­facts. RAW files con­tain more infor­ma­tion and are more com­press­ible.

The lev­el of JPEG com­pres­sion increas­es from right to left, there are more arti­facts. Source: Wiki­me­dia Com­mons

RAW pro­cess­ing does not make any changes to the orig­i­nal file. All set­tings are saved sep­a­rate­ly, so the source can­not be cor­rupt­ed. To get an edit­ed image, the RAW file must be con­vert­ed into a fin­ished image with the select­ed set­tings.

Disadvantages of RAW

The short­com­ings of RAW are in the vol­ume and speed of record­ing. If you shoot strict­ly in RAW, the mem­o­ry card will fill up faster, and the num­ber of frames per sec­ond will decrease com­pared to JPEG.

In addi­tion, RAW does not have a sin­gle encod­ing stan­dard, each man­u­fac­tur­er defines it sep­a­rate­ly, they also cre­ate their own soft­ware (called RAW con­vert­ers) for pro­cess­ing images in this for­mat. For users, this means that the soft­ware can choose depend­ing on which man­u­fac­tur­er’s cam­era they have.

For exam­ple, Nikon cam­eras encode RAW in NEF/NRW for­mat, and the con­vert­er that comes with the cam­era for free can only work with files in this for­mat. There are also uni­ver­sal pro­grams that sup­port most RAW encod­ings. Let’s con­sid­er each of these types sep­a­rate­ly.

Programs for working with RAW

Cap­ture NX‑D

Sup­plied with the cam­era on a CD. You can also down­load the lat­est ver­sion from the Nikon web­site. Sup­ports Win­dows and MacOS.

The pro­gram allows you to quick­ly adjust the white bal­ance: just use the eye­drop­per tool to spec­i­fy a place in the pho­to that will be tak­en as a ref­er­ence point when adjust­ing the white bal­ance. It can also be adjust­ed man­u­al­ly using the “col­or tem­per­a­ture” and “shift” slid­ers.

Adjust­ing the col­ors of an image in Cap­ture NX‑D. Source: Nikon web­site

There is a hori­zon align­ment func­tion, for this you need to draw a line along which the pho­to will be aligned. By adjust­ing the expo­sure, you can adjust the bright­ness of the pic­ture. The High­lights Pro­tec­tion and Shad­ows Pro­tec­tion slid­ers bring out details in the high­lights and shad­ows of the frame.

Hori­zon align­ment in Cap­ture NX‑D. Source: prophotos.ru

The “noise reduc­tion” func­tion elim­i­nates dig­i­tal noise that occurs if the pic­ture was tak­en at a high ISO val­ue or when the bright­ness was raised too much dur­ing pro­cess­ing. Noise reduc­tion has two slid­ers: “Inten­si­ty” and “Sharp­ness”. If you twist the first one too much, you run the risk of los­ing small details in the pic­ture, you can try to restore them using the sec­ond slid­er.

Pro­cess­ing ends with export­ing the image to JPEG or TIFF (it weighs more than JPEG, because it saves the image with­out loss in com­pres­sion).

Dig­i­tal Pho­to Pro­fes­sion­al

Soft­ware for own­ers of Canon cam­eras. To down­load, you need to spec­i­fy the ser­i­al num­ber of the cam­era on the Canon web­site. Sup­ports Win­dows, Lin­ux and Mac.

Rough adjust­ment of bright­ness, white bal­ance can be done by thumb­nail, and then con­vert, for exam­ple, a batch of pho­tos into JPEG using the batch pro­cess­ing func­tion.

More fine-tun­ing, in addi­tion to the func­tions list­ed in Cap­ture NX-D4, allows you to adjust the col­or inter­po­la­tion.

Imag­ine Edge Desk­top

RAW con­vert­er for Sony cam­eras, there are ver­sions for Win­dows and MacOS. It is notable for the pres­ence of the func­tion of remote con­trol of the cam­era when con­nect­ed via Wi-Fi or USB.

Raw File Con­vert­er EX 3.0

Fuji­film’s cam­era soft­ware runs on MacOS and Win­dows and is gen­er­al­ly on par with oth­er free con­vert­ers.

Raw Ther­a­pee

Cross-plat­form (Win­dows, Lin­ux and MacOS) and free con­vert­er, but quite slow. There are so many func­tions in it that their analy­sis is enough for a sep­a­rate arti­cle.

The pro­cess­ing process in this soft­ware begins with the already men­tioned dema­triza­tion pro­ce­dure. Raw Ther­a­pee offers dif­fer­ent dema­triza­tion algo­rithms for the user’s choice. There are a lot of algo­rithms — some work out the details well, oth­ers show the right col­or bet­ter. There is no best algo­rithm, each one is suit­able for its own sit­u­a­tion, so the scope for exper­i­men­ta­tion is immense.

IGV dema­triza­tion algo­rithm. Source: instantframe.ru

AMaZE dema­triza­tion algo­rithm. Source: instantframe.ru As you can see, the dif­fer­ence between the algo­rithms is neg­li­gi­ble.

Next, the pro­gram offers the usu­al steps for a RAW con­vert­er: expo­sure and image geom­e­try cor­rec­tion, white bal­ance and col­or bal­ance cor­rec­tions, noise removal, sharp­ness cor­rec­tion.

Raw Pho­to Proces­sor

A free con­vert­er that works exclu­sive­ly on MacOS.

The pro­gram con­tains film pro­files, cap­ti­vates with a sim­ple inter­face and good pic­ture qual­i­ty.

Cap­ture One

Paid con­vert­er avail­able on Win­dows and MacOS. A month­ly sub­scrip­tion costs about $28.

The con­vert­er is dis­tin­guished by the sup­port of ICC cam­era pro­files (i.e. col­or pro­files — data on how the same col­or looks on dif­fer­ent cam­eras) and a high­ly cus­tomiz­able inter­face. Cap­ture One has a whole arse­nal for work­ing with col­or, and work­ing with lay­ers in it is imple­ment­ed exact­ly like in Pho­to­shop. If you mask one or anoth­er object in the frame, you can process it sep­a­rate­ly from the rest of the pho­to.

Adobe Cam­era Raw

Tiny plu­g­in for Adobe Pho­to­shop.

By default, it offers auto­mat­ic set­tings for the main expo­sure para­me­ters, and if it detects over­ex­posed areas in the frame, it reports about it. If dur­ing pro­cess­ing you vio­lat­ed the expo­sure your­self, the plu­g­in will also warn you about this. It does not have batch pro­cess­ing tools, but Pho­to­shop itself will help with this.

Details on how to use the plu­g­in can be found here.

Adobe Pho­to­shop Light­room

Sep­a­rate paid soft­ware from Adobe. It has few dif­fer­ences from Cam­era Raw, the main thing is the pres­ence of cat­a­loging and sup­port for its own plu­g­ins.

Conclusion

RAW is not a uni­ver­sal replace­ment for all oth­er image encod­ing for­mats. But it’s a use­ful tool that will open up new cre­ative pos­si­bil­i­ties and ways to cor­rect mis­takes while shoot­ing.

The main pros and cons to remem­ber about RAW:

- RAW is the orig­i­nal data tak­en direct­ly from the cam­er­a’s matrix. The advan­tage of the for­mat is that no cor­rec­tions are applied to the image, and all fur­ther pro­cess­ing is giv­en to the user. This is not the case with JPEGs.

— The main dis­ad­van­tages of RAW: file size, shoot­ing speed and lack of cod­ing uni­fi­ca­tion.