HDR

HDR

HDR ali high dinamyc range. Je fotografija z obvezno obdelavo v računalniku. Tipalo na fotokameri ni tako (niti blizu) dobro kot receprtorji svetlobe v naših očeh. Naše oči so najboljša kamera. Ne znajo določit beline svetlobe (slika je modrikasta ali preveč rumenkasta) in ne znajo uravnavat svetlobe.

Zato, kadar slikamo pokrajino in vzamemo v zakup pravilo "grške sredine" dobimo lepo osvetljen travnik z nekaj drevesi. Kaj pa nebo? Vemo da je bil dan lepo sončen, sonce je mižikalo skozi oblake, vendar je na sliki popolnoma belo. Belo in brez oblačaka, kje je pa modrina?

V primeru, da zajamemo nebo, kjer sonce ponovno meika skozi oblake, dobimo prelepo modro nebo, vendar na pokrajini je pa samo še senca.

HDR fotografija odpravi težave s kompleksnimi svetlobnimi pogoji. Kaj naredimo? Slikamo najmanj 3x ali večkrat isto kompozicijo s stojala. Pri tem mora biti ena slika normalne osvetlitve, druga preosvetljena in treja podosvetlejna. Slike nato naložimo v program, ki jih zloži eno na drugo preko zelo zapletenih algoritmov. Naprej je pa samo še igra kreativnosti.

Kateri programi? Jaz osebno delam s photomatixom in photoshopom CS5. Novi CS 5 je dodobra izboljšal prijaznost do uporabnika. Razlika? Po mojih izkušnjah je CS 5 oziroma photoshop bolj oster in naredi bolj realen rezultat. Medtem ko photomatix naredi bolj ne vem kako bi rekel, morda slikasto sliko.

Dobra navodila ponuja tale stric na tem linku: http://www.stuckincustoms.com/hdr-tutorial/, kjer so tudi primeri, ki premagajo moje patetične slikce, še posebej pa prve poskuse, ki so prikazani v tem postu. Aja HDR se da delat tudi iz ene same slike, vendar pravijo ,da to ni čisto pravi HDR.

Torej kaj potrebujemo za HDR?

• STOJALO ;
• Fotoapart (DSLR) ali pa morda kompaktni (priporočljivo je slikati v RAW formatu in ne JPEG, saj RAW format vsebuje bistveno več informacij o svetlobi, kar pripomore k bolj ekstremni obdelavi slike);
• Nastavitev na bracket mode, kjer nastavimo različne osvetlitve;
• Avtosprožilec (da ne zamajemo fotokamere, ki je tudi na stojalu lahko zatresena);
• Programsko opremo za obdelavo (jaz, kot rečeno uporabljam photmatix ali pa photoshop CS 5);
• Kompleksne svetlobne pogoje;
• Kreativnost (ki jo še pilim ;)
• Pripravljenost iti ven in raziskovat.
•  SLABOSTI: ni dobra tehnika za premikajoče objekte (tudi piš vetra lahko pokvari sliko, ko se veje na drevseu premikajo)
Manjša ostrina slike in vačsih nerelani rezultati

HDR stands for high dynamic range. Now what is is it all about. It's part of photography which involves a certain degree of computer retouching. A photocamera sensor, even though the high price is not perfect. Our eyes can read White balance and exposure far, far better than electronic sensor in our photocameras. Eyes are still the best sensor around. They now how to fine balance and expose shadow and sky.
What am I talking about here is: Do you remmember taking a landscape photo on bright sunny day with beautiful blue sky and few white clouds. But when you downloaded picture to your computer, the bushes seem fine, corectly exposed. Where is the sky? There is just a white strip without any clouds. What happened? Your sensor together with metering mode (we have got matrix, center weigh and spot mode) took light information of the bushes, which are green and have just the right light reflection value (Your camera has zeroed the correct exposure) and brighten the shadows. Sky is because of that overexposed usualy (depens on position of the sun, etc) So when we have complexe light conditions we take at least three pictures (one correctly exposed, one underexposed and overexposed). We achive that usualy by going into camera bracketing mode.
After we have taken our pictures, we of course download them to our computer and stack them one on top of the other with appropriate software. I usually use photoshop CS 5 or Phortomatix 4. I aslo suggest using two more plug ins fot Photoshop (Topaz Adjust an Imagenomic noiseware) Photoshop somehow creates more realisitc images that are sharper and it has great feature for removing ghosting effects for moving objects. While the latter creates more surreal pictures.You shold make final adjustemnts in photoshop and use the add-ons I've mentioned. There are no rules, just use your imagination and creativity. This link will tell you more and it contains better examples than mine below. So what do you need:
tripod

• photocamera with A, S or M mode and with posibility of bracketing exposures, i suggest shooting in RAW format, which contains more data about the light
• timer shutter or remote (so you don't shake the photocamera)
• composition without movement
• complex lightning situation
• software and computer
• PROS: deals good with complex lightning situation
• CONS: cant's shoot movement and sometimes surreal results, some photographers don't like HDR of that. Sharpness in not that good.