{"id":596,"date":"2013-11-30T18:04:34","date_gmt":"2013-11-30T23:04:34","guid":{"rendered":"http:\/\/richeskinphoto.com\/blog\/?p=596"},"modified":"2016-04-29T14:39:30","modified_gmt":"2016-04-29T18:39:30","slug":"multi-image-photography-part-iv-hdr","status":"publish","type":"post","link":"https:\/\/richeskinphoto.com\/blog\/?p=596","title":{"rendered":"Multi-image Photography: Part IV \u2013 HDR"},"content":{"rendered":"

“The secret of a good photograph\u2014which, like a work of art, can have esthetic qualities\u2014is its realism … Let us therefore leave art to artists and endeavor to create, with the means peculiar to photography and without borrowing from art, photographs which will last because of their photographic qualities.<\/i>” — Albert Renger-Patzsch<\/p>\n

High Dynamic Range photography combines multiple images with bracketed exposures to compress the brightness range of scenes where very bright areas and very dark exceed the capture range of the sensor.\u00a0 In such scenes an average exposure might result in shadow or highlight areas without detail (highlights completely \u201cblown out.)\u201d<\/p>\n

With film, if there were foreground\/background brightness differences, such scenes might have been clumsily handled with a graduated neutral density filter (of course grad filters can also work for digital photography, but HDR is far more flexible).\u00a0 These filters would have half their areas darkened by the equivalent of 1, 2 or 3 stops with a neutral gray that wouldn\u2019t change colors or tones, and the remainder clear.\u00a0 If you had for example a sunset that was sufficiently bright that a proper exposure left the foreground dark, you could use this filter to hold back light from the sky and even out the exposure.\u00a0 This worked fairly well where you had a straight horizon, but not so well in more complex situations.\u00a0 Another solution to long tonal range was to \u201cexpose for the shadows and develop for the highlights,\u201d which worked well for black and white film but not so much for transparencies. Using flash or fill flash and dodging and burning in the darkroom were other means of handling scenes with long tonal values.<\/p>\n

One of the draw backs of HDR is that the subject and camera need to be still or you capture the movement through the bracket set.\u00a0 This is called ghosting. A common ghosting problem for example is the movement of clouds in the sky.\u00a0 Several of the programs that do HDR can now handle some ghosting by allowing you to pick a particular exposure from the set to use for areas that exhibit movement.<\/p>\n

A typical DSLR sensor can capture a range of about 9 stops.\u00a0 Black and white negative film can capture about 13 stops and a view through a window from a dim interior to bright sunlight would be about 12-14 stops.\u00a0 On the other side of the process, the best possible paper is going to able to portray only about 7 stops (Freeman).\u00a0 So somewhere in the process there is need to compress the brightness \u00a0range of high dynamic range images.<\/p>\n

When planning to shoot for HDR processing it is very helpful if you have tripod so that the images, especially those with the longest shutter speeds can be properly aligned.\u00a0 If you don\u2019t have a tripod, increase your ISO if possible so that even the longest exposures will be steady (this will add noise to your darkest exposure).\u00a0 Bracing against a solid object such as a fence post or tree can also help to avoid camera movement. \u00a0Setting up an auto bracket now becomes more important so you don’t move the camera to make adjustments, but can just press the shutter the requisite number of times.<\/p>\n

Set your exposure to manual and adjust the exposure using only the shutter speed.\u00a0 If you change the f-stop, the foreground\/background focus may change, decreasing sharpness in the final image or making alignment more difficult.<\/p>\n

The number of exposures will be dependent on the total range over which you make your exposures and the steps in between. Being sure to fully capture shadows and highlights will determine the range.\u00a0 Usually steps of 2 stops will be sufficient.\u00a0 You can start with your shortest exposures (the histogram is bunched to the left) so that the rightmost histogram values are to the left of the center of the axis.\u00a0 Lengthen your shutter speed in two stop increments (expose to the right) until the histogram is bunched up on the right and the leftmost values are to the right of the center of the axis.<\/p>\n

To facilitate processing in Photoshop, I shoot my hand at the beginning and end of each sequence to make it easier to see where the sequence begins and ends. \u00a0When naming the files I use a scene name, followed by the number of the HDR sequence for that scene, followed by a letter for the frame sequence. \u00a0This can be done automatically in Batch Rename under the tools menu. So for example The first pan of a river gorge scene might be RiverGorgeHDR1a, RiverGorgeHDR1b, RiverGorgeHDR1c. If I shot a second pan sequence it would be RiverGorgeHDR2a, RiverGorgeHDR2b, etc.\u00a0 When naming the final merged image it would be, for example, River GorgeHDR2, which would enable to go back to the original HDR sequence of images if I ever needed to.<\/p>\n

I usually shoot in RAW, so to begin I select the images in Bridge and double click on one to open them all in camera RAW. \u00a0I make lens and chromatic aberration corrections from the lens corrections tab. \u00a0I then make other global changes such as exposure, saturation or clarity. I don\u2019t make local corrections such as spot removal. Then \u201cselect all\u201d on the left and then synchronize. Click OK if you have not made local corrections; if you have, just unclick those such as spot removal or local corrections. This will make the same changes to all of the images so they remain consistent. \u00a0Then in Photoshop click Alt-open to Open copies.\u00a0 Photoshop will open all of the images.<\/p>\n

When that is complete, File > Automate > Merge to HDR. Click \u201cAdd Open Files.\u201d \u201cAttempt to Automatically Align Source Images\u201d should be selected by default and click OK. \u00a0Photoshop will open a dialog box with the merged image and the component images across the bottom indicating the relative exposure.<\/p>\n

In the upper left corner is a check box to \u201cRemove Ghosts\u201d \u2013 click that because even on a tripod there might be slight movement from the mirror slap or pressing the shutter. Just below the Ghost checkbox it will provide options for Mode:\u00a0 8, 16 or 32 bit.\u00a0 I generally leave it on 16, unless my camera only took 8-bit images, then there is no advantage to 16 bit. \u00a0Next to mode are the tone mapping options.\u00a0 Local adaptation is generally most useful and comes up by default.\u00a0 Highlight compression produces a relatively flat image that might be useful in some instances with additional processing after generating the HDR.\u00a0 Under Tone and Detail I usually tweak the detail up a bit and hold off on Gamma and Exposure until I am done with \u201cCurve.\u201d\u00a0 The curve can be used like a curve adjustment layer.\u00a0 If you click on \u201cAdvanced\u201d you can use simple sliders to adjust Shadows, Highlights, Vibrance and Saturation.\u00a0 Click OK to create the merged image, and editing according to your own workflow from there.<\/p>\n

After Google bought NIK, they offered a good deal on a package of NIK software that included HDREfexPro 2 which also offers HDR and tone mapping tools.\u00a0 Again open your files and make global corrections.\u00a0 Open HDREfexPro 2 and click on \u201cAdd open files.\u201d\u00a0 Smart Object will be checked by default.\u00a0 If you want to generate the HDR as a Smart Object then click on \u201cMerge dialog.\u201d However, as a Smart Object you won\u2019t have access to curves, contrast or an overlay adjustment layers in the final HDR image.\u00a0 Since there were relatively few changes to make in the HDR dialog, I would not generally expect to go back, and wouldn\u2019t open as a Smart Object so I have more flexibility for subsequent adjustments.<\/p>\n

The ensuing dialog has some similarities to PS, with a large rendering of the HDR image and small images showing the range of images used.\u00a0 An option is not offered for different tone operators, but an option is provided for correcting chromatic aberrations which can occur as a result of the tone mapping.\u00a0 If you see aberrations, correct then, otherwise click \u201cCreate HDR.\u201d HDR Efex Pro gave a much different result then PS, with a much flatter image and both the shadows and highlights brought toward the midtones.\u00a0 I thought the image less interesting than the PS result, but could make subsequent changes. Clicking OK opened the image back in PS as a 32-bit TIFF file.<\/p>\n

\"RiverGorgeHDR5d\"<\/a><\/p>\n

This is the best single image corrected with typical local and global controls, including selection and darkening of the sky, overlay, etc.<\/p>\n

\"RiverGorgeHDRPS\"<\/a><\/p>\n

This image is the Photoshop HDR result.<\/p>\n

 <\/p>\n

 <\/p>\n

 <\/p>\n

\"RiverGorgeHDNIK<\/a><\/p>\n

This is the NIK HDR result, and<\/p>\n

\"RiverGorgeHDNIKMOD\"<\/a><\/p>\n

This is the NIK HDR modified by normal workflow after generation of the HDR. You can see that the detail in the shadows is increased for both the cliff and the river.<\/p>\n

 <\/p>\n

 <\/p>\n

Michael Freeman, Mastering HDR Photography, Amphoto Books, 2008)<\/p>\n","protected":false},"excerpt":{"rendered":"

“The secret of a good photograph\u2014which, like a work of art, can have esthetic qualities\u2014is its realism … Let us therefore leave art to artists and endeavor to create, with the means peculiar to photography and without borrowing from art, … Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[],"tags":[4,34],"class_list":["post-596","post","type-post","status-publish","format-standard","hentry","tag-in-the-field","tag-multi-image"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p8lcUy-9C","_links":{"self":[{"href":"https:\/\/richeskinphoto.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/596","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/richeskinphoto.com\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/richeskinphoto.com\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/richeskinphoto.com\/blog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/richeskinphoto.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=596"}],"version-history":[{"count":9,"href":"https:\/\/richeskinphoto.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/596\/revisions"}],"predecessor-version":[{"id":611,"href":"https:\/\/richeskinphoto.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/596\/revisions\/611"}],"wp:attachment":[{"href":"https:\/\/richeskinphoto.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=596"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/richeskinphoto.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=596"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/richeskinphoto.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=596"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}