At Arc Desktop 10.6.1, I have an aerial photo tif image: 4-band (RGBA), 16-bit, unsigned integer. When displayed, it shows as natural-color. Here's a screen snip of just a small portion of the image:
The image's file size - 14 GB(!) - is too great. I suspect the large file size results from its 3-inch pixel resolution and 4 bands.
I would like to reduce the image's file size, while a) keeping the same pixel dimensions, and b) retaining some degree of the original color. In other words, I'm willing to accept a limited range of colors in the output if I can keep the 3-inch pixel size. Given the 3-inch constraint, my only option appears to be to reduce the number of bands to one.
If a single-band output could be achieved with 16-bit color, its resulting 65,536 colors just might be enough. I need to answer that question, but have not yet been able to output such a single-band color image.
This screen snip shows conceptually what I would like to accomplish in Arc:
Although this example utilized satellite imagery, and outputs to a false-color image, it shows my train of thought: reduce file size by merging the RGB bands into a single output band containing some degree of color.
Efforts to date:
I've been able to create a single-band grey image using this flow:
- Using the Arcmap > Windows > Image Analysis tool, Clip the source image
- In the ensuing raster Layer Properties > Functions > R-click > Insert Function > Grayscale Function > apply equal weights to R, G, and B.
The output image is now single-band, 16-bit, and it's file size is reduced from 14 GB to 3 GB. Good news, but unfortunately it's not color...
I've tried other functions in addition to Grayscale, but to no avail.
How can I merge the multiple bands into a single color band, using Arc?