Better Light 7 instruction

fewer, eﬀectively larger pixels. This process always samples the entire image area, does not skip lines, and thus is immune to aliasing caused by subsampling (skipping pixels).

These lower resolution selections average more CCD data values together to produce the larger pixels; this averaging lowers the CCD noise levels, and increases the bit depth of the image beyond the speciﬁcations of the (14-bit) data converters alone. The noise reduction is more apparent in images captured at higher ISO sensitivity settings, which may allow the use of very high ISO settings when low-resolution image ﬁles are being captured. The bit depth improvement will be most notice- able at lower ISO sensitivity settings, where CCD noise does not limit the available dynamic range.

For resolutions greater than 100% (SuperModels only), the scanned width of each line is decreased by reducing the distance the sensor moves in the insert, thus adding additional real pixels between the positions normally scanned. In the direction of the sensor (short dimension), interpola- tion is used to redistribute the captured information over additional pixels. Since the scan direction (long dimension) is always giving real pixels, the result is more accurate than techniques that interpo- late in both directions and results in sharper images. In the worst case, 3 pixels are made from 2 real pixels.

If an exact image output size cannot be obtained at one of the available resolution selec- tions, it is usually better to select a resolution that produces a ﬁle larger than needed, and subsequently reduce it to size in an image editor like Photoshop.

In many cases, but not all, cropping can be used in conjunction with the resolution selections to produce the exact ﬁle size required. This method may involve changing the camera position or magni- ﬁcation (image size) to ﬁt the image into the desired crop box. The choice of predetermining the exact camera positioning and the speciﬁc ﬁle size, or post-adjusting an image to a given ﬁle size, will often depend on the number of images being captured. Post-adjusting image data may be faster than repo- sitioning the view camera for a few images, but the time can add up if many similar images are being produced.

For a given scan area, lower resolution settings also produce shorter scan times due to the require- ment for fewer lines in the scan. This relationship is linear; for example, reducing the number of lines by half will halve the scan time.