Go Back   RetouchPRO > Technique > HDR, Panoramas and Tone Mapping
Register Blogs FAQ Site Nav Search Today's Posts Mark Forums Read

HDR, Panoramas and Tone Mapping Merging several different exposures into a single image

A question about doing HDR from one image file

Thread Tools
Old 11-26-2007, 10:58 AM
PhotoShopNoobie PhotoShopNoobie is offline
Junior Member
Join Date: Nov 2007
Posts: 5
A question about doing HDR from one image file

Ok, is there any drawbacks (negatives) to doing HDR from a single RAW image?

Is there any loss of detail? An increase in noise?
Reply With Quote top
Old 11-27-2007, 01:18 AM
crazyfly1's Avatar
crazyfly1 crazyfly1 is offline
Senior Member
Join Date: Jan 2007
Location: Colorado Springs Co. USA
Posts: 733
Re: A question about doing HDR from one image file

Hi photoshopnoobie,
My opinion follows;
Yes, yes, and yes.
HDR stands for High Dynamic Range. The purpose is to take two or three different exposures of the same image and blend them taking the best exposed portions of each image.
You might have seen images or training videos where a landscape is blended from two exposures, one exposed for the sky and one for the ground. Two layers are made one containing each image and the two are blended using masks to make one image that is well exposed throughout.
Same idea only done with a program (I use Photoshop cs3 Extended) that will take the best exposed pixels from the leaf of a tree or the rock that maybe got blown out with a reflection in one exposure but not the other two, (and here's the main thing) and cram all the best info from all 3 into 32 bits, a space that is soooo much bigger than 8 bit it baffles the mind.
The problem with trying to do that with one photo is that if the rock or face or sky is blown out, meaning if the RG and B channels are at or passed 255 then there is no information there...none. there is no way to make it be there. If the channels are absolute black then there is nothing there. If you have a blown out sky there simply is no magic you can do with photoshop to make it come back, all you can do is darken it and color it in.
I've seen a lot of really pretty, painterly pictures that are refered to as HDR, alot of them have incredibly saturated colors. Being able to push the colors is a bi-product of having an HDR image, a 32 bit image, being able to push up the vibrancy without making a mess of color is not necicarily the point of HDR.

Hope that helps.
Reply With Quote top
Old 11-27-2007, 03:39 AM
saby's Avatar
saby saby is offline
Senior Member
Join Date: Jul 2004
Location: Beeston Nott'm
Posts: 449
Re: A question about doing HDR from one image file

I've to agree with crazyfly real hdr is from several ldr files so U couldn't do it even from single raw(16bit), because U've not enought information for 32bit. Actually I very often use one file hdr- forgive me crazyfly- to get my image more detailed, what is like a local contrast enchantment:

one file jpg tonemapped:

and original linked here

Details can loss by increscent noise but U can control it by the tonemapper.

Attached Images
File Type: jpg orig.jpg (100.0 KB, 70 views)

Last edited by saby; 11-27-2007 at 03:51 AM.
Reply With Quote top
Old 11-27-2007, 10:01 PM
Robt Robt is offline
Senior Member
Join Date: Apr 2004
Location: Seattle
Posts: 131
Re: A question about doing HDR from one image file

I tried to shoot a couple of images to see this HDR but I wasn't impressed. Now that I see a whole section on the subject, I'll wall off a few hours and see what you will teach me.
Reply With Quote top

  RetouchPRO > Technique > HDR, Panoramas and Tone Mapping

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Posting Your Image and Works Etiquette Craig Walters Photo Restoration 27 09-26-2016 11:30 AM
Tutorial 05: Converting a Color Image to Black and White grayscale BW DannyRaphael Photo-Art 101 17 05-22-2011 04:55 PM
List of HDR and Tone Mapping Software Doug Nelson HDR, Panoramas and Tone Mapping 32 04-21-2011 01:59 AM
Film scanner for home use? bodegg Hardware 12 05-20-2007 11:40 AM
Newbie printing question Doug Nelson Input/Output/Workflow 0 08-08-2001 11:30 AM

All times are GMT -6. The time now is 05:28 AM.

Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2016, Jelsoft Enterprises Ltd.
SEO by vBSEO ©2011, Crawlability, Inc.
Copyright © 2016 Doug Nelson. All Rights Reserved