HDR Research

HDRI stands for High Dynamic Range Imaging, which is a method that allows the photograph to have much higher dynamic range between the lightest part of the image and the darkest.

HDR is useful because:

When you take a photograph of a scene the camera will either allow the light parts of the image become blown out to have the darkest parts correctly exposed or the darkest part of the image underexposed to have the light part correctly metered.

If you set the camera to bracket the exposure of a scene (meaning you can purposely under and over expose the image) and take multiple shots of the same scene,  in post production using software you can merge all the exposures together to create an image that incorporates the exposures of all the images you took and this is called an HDR image.

The tools used to perform the technique

The HDR pro option in Photoshop CS2-CS6

Image mode (changing from 32 bit to 16 or 8 bit)

adjustments to

Curves

HDR toning

Gamma

Detail

Shadow

Vibrance

Saturation

*Capturing tips - only change the camera's shutter speed to adjust the exposure not the aperture because you need the Depth of Field to remain the same throughout the bracketed shots.*

Once you have taken the bracketed shots using your DSLR and tripod,  open up Photoshop and open the HDR pro option. (Choose File>Automate >Merge to HDR Pro) (you can also can use a software called Photomatrix)

When all the images files have been selected select merge, your three or more photos are now a 32 bit floating point image. It is a good idea to save this master file as a PSD file so you can always come back to the original merged HDR image.

Now you need to convert the 32 bit file into a 16 bit or 8 bit so you can edit the merged HDR image, do this by Choose Image>Mode>16 bit (or 8 bit). To do this correctly you need to tone map your image file before conversion.

Once your image file is an 8 bit you have the editing options available to you like exposure, gamma, edge glow, tone and detail and all the usual slider bars like highlights, shadows, saturation and vibrance. Once you’re happy with how the image looks you ok to convert and you are done!

Info on bits:

8 bit has 256 tones per channel 

16 bit image has 64 K !

32 bit floating point is unlimited  

References used to source the information.

Photoshop HDR tutorial. hdri, High Dynamic Range Photography. | Merging HDR in Photoshop Tutorial. 2013. Photoshop HDR tutorial. hdri, High Dynamic Range Photography. | Merging HDR in Photoshop Tutorial. [ONLINE] Available at: http://www.photoshopcafe.com/tutorials/HDR_ps/hdr-ps.htm. [Accessed 10 March 2013].

High dynamic range imaging - Wikipedia, the free encyclopedia. 2013. High dynamic range imaging - Wikipedia, the free encyclopedia. [ONLINE] Available at: http://en.wikipedia.org/wiki/High_dynamic_range_imaging. [Accessed 10 March 2013].