The options for Photographic Montages are the most extensive in i2k Retina:
Layout Options
Experimenting with these and understanding their behavior can improve your montages. i2k Retina offers four layout modes for photographic montages:
Auto
When Auto is selected, which is the default, i2k Retina automatically chooses between the three options, Cylindrical, Planar and Reposition. The automatic selection between these is based on evaluating what each does to the photos in a particular montage and choosing the one that appears to be the best. Instead of letting i2k Retina choose the layout automatically, you may choose one of the three options yourself.
Cylindrical
This is most appropriate when the images are taken by sweeping the camera left-to-right or right-to-left, perhaps using multiple levels of sweeps. Cylindrical maps the photos onto a virtual cylinder and then unwraps the cylinder to create the flat montage. In doing so, some curving can be introduced near the top and bottom of the montage.
Planar
This is most appropriate when taking pictures of something flat, such as the facade of a building or a painting. Planar maps all the photos onto a single flat surface. Photos well-away from the center of the montage may become somewhat stretched during this process.
Reposition
This is a simplified version of both cylindrical and planar and may be used when the main subject is far from the photographer and there is little of specific interest near the top or bottom of the photos (e.g. sky in the top third and water in the bottom third). Reposition also places the photos on a flat surface, but only does so by moving the individuals photos up, down, left and right. This does not allow enough flexibility to create seamless montages, especially on the top and the bottom, but sometimes the magic of seam selection can hide the visual differences, for example in the clouds of the sky and the ripples of the water. When Reposition creates a seamless montage, it is the best choice of all, but look at your results carefully. Also, on rare occasions, reposition may be the ONLY layout option that works.
Final Montage Crop Option
When i2k Retina forms the montage, the outlines of the photos will form an irregular shape, especially when many photos are being combined. Most users will want this montage cropped to a rectangular final image. i2k Retina finds the largest possible rectangle that fits inside the montage, and then decides whether or not to crop. This decision is controlled by the prior selection of buttons:
- The Auto button indicates that i2k Retina should crop the montage as long as enough of the image area is preserved within the rectangle. The percentage of area that must be preserved in order for cropping is controlled as a user preference.
- The Always Crop button tells i2k Retina to crop the montage no matter how much montage area is outside the largest possible rectangle.
- The Never Crop button tells i2k Retina to leave the montage uncropped.
Radiance Image
During montage generation, i2k Retina estimates properties of the camera and the lens as the basis for combining the photos. In doing so, it also estimates the amount of light - the "radiance" that formed each pixel. When generating the final montage, the radiance values are converted back to colors. This conversion balances the twin goals of preserving the original colors taken by the camera and combining the photos into a pleasing, seamless whole.
In most cases, this works just fine. Advanced users wanting more control over the final pixel colors and brightness values, may want i2k Retina to stop with the radiance values, saving them as a "Radiance Image". This option is most useful when scene has significant brightness variation, with photos being taken in and out of shadows.
The Radiance Image is akin to a High-Dynamic Range image, although it is acquired by moving the field of view of the camera rather than by fixing the field of view and taking multiple exposures. The result is stored in a 16-bit-per-color TIFF image (ordinary TIFF images have 8-bits per color). Users not familiar with the properties of image radiance will notice that the resulting montage has a dark appearance, almost like the shadows and darkening of the sky at dusk.
In short, i2k Retina effectively offers two options in handling the colors and brightness values. The default option generates as faithful a combination of the original photo values as possible. The Radiance Image option generates values roughly proportional to the original radiance values, allowing the user to create the final colors from these using a different tool.
Aggressive Registration
Clicking this button tells i2k Retina to be more aggressive than usual in trying to align each pair of images. This allows it to handle tougher cases while taking a bit more computation time, but also, on rare occasions, causes it to make some mistakes. On rare occasions this leads i2k Retina to make mistakes. Aggressive registration is not recommended for photographic image montage, except in very rare circumstances.
