Tips for post processing Panoramic Images
This article is a follow up article on Panoramic Images that I published in the March 2013 newsletter. If you missed that newsletter just send me an email and I will resend that newsletter to you.
Post processing and stitching a panoramic image goes much easier if you capture the original images properly. Make sure you follow good workflow in the camera stage-it will pay you dividends later when you are sitting down to the computer to finish the image.
This tutorial assumes that you are using Photoshop and processing your images in Camera Raw. This tutorial does not cover basic use of Camera Raw for post processing your images. If you need help with basic post processing and using Camera Raw I have developed a series of Youtube videos that will take you through some of the post processing steps.
Choose the image frames that you want to stitch. If you remembered to put a blank frame at the beginning and end of your series this is an easy process. In Bridge select the first image, hold the shift key and select the last image in the series, right click and select “Open in Camera Raw”. All of your selected images will open in Camera Raw, now “Select All” at the top left of the screen and make the same batch edits to all of your images equally.
Image resolution: you may not need your native camera resolution for your final stitched image file. Depending upon how large you intend to make your final print will determine how large your individual file size needs to be prior to converting the images to tiff or psd format. If you made your original image captures in vertical format you can use the longest dimension to figure out what size you need to select for converting your files. Figure about 240 pixels per inch for making a print. So a 3200 pixel image on the long dimension will make a print that is slightly over 13 inches high by how ever long the image turns out to be. If you have a 17megapixel camera then your long dimension will be about 5100 pixels and your panoramic will be over 21 inches high-more than enough for most panoramas. Most stitching problems arise because your final stitched image will have a file size that is larger than your computer’s computing capabilities.
Post process your selected images and place them in a separate folder. Open the folder in Bridge. Highlight the first and last of the series while holding the shift key. From the “Tools” pull down menu select: Photoshop-photomerge.
A dialog box will open with several options:
Layout: Auto is usually the best option here especially if you are stitching natural landscape images. If you are stitching architectural images try the Perspective setting. Cylindrical and Spherical settings are if you are stitching images for use in an application where you want to examine the 3 dimensional aspects of an image from either a perspective of inside or outside the object. Collage and Reposition are useful for creating special viewing effects where you may want to reveal or call attention to the distinct separate qualities of each individual image frame. For the purposes of “natural landscape panorama” the blending qualities of the Auto setting are the best.
Boxes at the bottom should be checked as follows: Blend Images Together-yes check this box, Vignette Removal-no, this should have been done in the post processing above, Geometric Distortion Correction-no, again this should have been done in the post processing.
You are now ready to merge your photos.
Once you have merged your photos I usually zoom in and look around the image. I make sure all horizon lines and other elements have blended properly.
A couple of problems that may arise and how to fix:
Image does not blend resulting in a series of images that overlap and the edges are apparent. Fix-make sure you are only using the file size you need, this usually happens when you are trying to stitch a panorama that will exceed your computer’s computing power. Empty your cache and try stitching again, or reprocess original images at a smaller image file size.
Horizon line does not blend or does not line up from one image to the next. Fix-make sure you have selected the “Enable Lens Profile Corrections” in the Lens Corrections area of Camera Raw. If this does not fix the problem you may need to adjust individual layers in the final stitched image. In the “Layers” menu select an individual layer, using the move tool move or adjust the layer so the horizon line or other element blends. This fix will usually create problems someplace else; if this is the case you will need to correct to the least problematic fix and use the clone tool or other blending tool to fix any imperfections.
Once you determine that the image has blended properly you should “Flatten Image” under the “Layers” drop down menu. Crop the image and fix any imperfections on the edges where the image did not quite fit to the rectangle of the cropped image. A note about cropping–if the image was shot correctly the horizon line will be in the middle of the image in the final stitched image, cropping the final stitched image will adjust the horizon up or down as desired. If the image was shot in vertical format there will be plenty of pixels left for enlargement.
Presto! You have a panorama!