High Dynamic Range Images or HDRi is a completely new photography technique that is used to extend the exposure range of a camera. Fhotoroom HDR provides the widest and most powerful selection of tools to take multiple exposure from a camera and align, merging, tone map and post process till your HDR is perfect.
To begin this tutorial it is assumed that you have a basic understanding of what HDR images are. If that is not the case, please read What is HDR tutorial. In addition, for this tutorial you need several photographs of the same image at different exposures (preferably captured using a tripod). If you don't please feel free to login and use any of the free photo sets available in the Fhotoroom group.
The first step in creating an HDR image is selecting your source photos which are simply a scene photographed at different EV levels with the fstop locked, if the fstop is allow to change then it will prevent the image from aligning properly. This is because each fstop distorts the image slightly differently giving a different DOF or depth of focus.
HDR Exposure Selection
To begin you first open the "Generate HDR Image..." tool in Fhotoroom located under the menu option called "HDR's". The window below appears and is the place where you define all the properties for creating your HDR image. It is highly recommend to always select the "Automatically align source photos", beyond that is very dependent on the scene that was taken and how it was taken. Shots take with a tripod probably don't need any auto alignment let alone rotation issues. The "Use Slow Method" is simply a slightly more complex method of auto alignment and can usually align photos that can't with the simpler method. The "Use Region for Auto Alignment" option allows the user to define an area (by selecting an area in the photo) in the image to focus alignment on, which is very useful for shots with a lot of distortion.
Usually the next scene after this one is the Manual Alignment override window, which shows you exactly how well Fhotoroom aligned the photos and then correct if necessary. Users can now by pass this window completely by selecting the "Bypass Manual Alignment Correction" option.
Now that the Alignment options have been selected users can define how they would like the merging to be done, with options such as creating an hdr file when needed, creating an hdr that are precise in luminosity values which important for Image Based Lighting in the 3D industry, Reduce Micro Noise, Reduce Ghosting which can occur when object, trees or people move between exposures and lastly Reduce Highlight Grey Areas.
There are 2 very important things to consider here, using the Ghosting option reduces the overall dynamic range of your hdr files which results in less detail and secondly the Reduce Highlights Grey Area should be selected if more than one exposure has very bright object such as the sun, lights and so forth.
Manual Alignment of Photos
If you choose to make additional manual corrections and wish to see how well the photos have been aligned, you select any photo other than the first photo on the list which is considered the master photo (the photo by which all other photos are aligned to).
Once selected the Alignment Preview Window gets updated with the new layer. To correct any misalignment, scrolling the up/down arrows of x Shift and y Shift slider options allows for pixel accurate correction. To make this process as simple and precise as possible, users can move the image position, zoom in and out and adjust the opacity of the image layers to allow for easier comparison. The opacity has no effect on the final result and is only used to help with alignment.
To see all the information related to each image you can scroll the image list to the right and see, fstop, exposure time, (x,y,a) alignment as well as image ranking or select each file individually.
Image List Checkbox
The Checkbox option beside each photo allows users to unselect any photo(s) they don't like or can't align properly before merging to the final image.
(X, Y, A) Precession Alignment & Auto Alignment
The X, Y and A alignment options allows the users to align the images to a master image before applying the hdr merge. The first image of the list is always the master image, and the order of the list presented has no effect as everything is ordered during the merging process.
The Freehand option was included in order to enabled users to align images in the same manner that you would move layers around in Fhotoroom. To utilize this option you require to check off the Freehand checkbox located to the right of the Alignment Tools title. Once finished, this box can simply be unchecked.
Step by Step
Goto HDR's | Generate HDR Image... menu option.
Once the "HDR Exposure Selection" window is open, click the Browse... button.
Select the files you want to use to create your hdr image.
Select your Auto Alignment and Merging options, highly recommend always have Auto Alignment selected.
Click Apply button. If the Bypass option was selected skip to step 8.
If you feel the misalignment was significant enough, and your image requires additional manual correction, then select each photo one by one and using the Hand, Zoom, and Opacity tools verify each photo's alignment. If you believe there maybe a misalignment, adjust the x Shift and y Shift values until the layer is properly positioned. This information is preserved in the Image List, which can be seen by scrolling the Image List to the right.
Click the Apply button to begin the merging process.
Once your merging operation is completed, Fhotoroom will ask if you want to Tone Map your image now. If additional editing is required before tone mapping simply select "No" and you will be able to tone map your image anytime using the HDR's | Tone Mapping... menu option. Once you are happy with your results you can save the image in any format available in Fhotoroom, either HDR or LDR formats.
Single File Tone Mapping
If you want to tone map a single jpg or raw file, simply load your photo into Fhotoroom and not into the Merge to HDR tool and then proceed directly to the HDR's | Tone Mapping... menu option and Fhotoroom will do the rest for you.
Goto File | Open... menu option.
Once file has been loaded goto HDR's | Tone Mapping... menu option.
If the file was one of the hdr file formats the Tone Mapping preview tool will automatically load. If the file was any other file format like a camera RAW or jpg, a popup option will load asking if you would like Fhotoroom to prepare this file by converting it into the hdr color space which is required for tone mapping. Once you click Yes, Fhotoroom will then load the Tone Mapping window.
To learn more about tone mapping you image go to our Tone Mapping tutorial.