KB10352 - Why would the file size of a TIFF image exported by the AIC be significantly larger than the source TIFF image?

There is no inherent reason why the file size of a TIFF image exported from the AIC must be larger than the size of the corresponding source TIFF image, after going though the PixelStore conversion process. The size increase that you report could be explained by one of the following possibilities:

- Your original image is composed of non square (rectangular shaped) pixels. The AIC converts rectangular shaped pixels into squares (for maximum compatibility with other software packages). If rectangular pixels are converted to square pixels, this would increase the number of pixels, resulting in up to a 30% increase in the size of the exported TIFF file.

- The input images are somehow compressed, which means you are comparing compressed source data with uncompressed output data. (The AIC does support export to the TIFF format with LZW compression.) - The source TIFF images are not full 24 bit (therefore not supporting an unlimited colors) and you are either 1) exporting to a 24 bit TIFF or 2) using the wrong bit level settings for the intermediary PixelStore format image.

- The input images used to create a mosaic are not all of the same resolution level (pixel density). In a mosaic situation involving source images of different resolution level levels, the AIC resamples any source imagery of a different resolution level to match the resolution level of the first image in the project list. If the resolution of the first image in the project list is significantly higher than the average of the other images, pixels will be added in the PixelStore output image, resulting in an increase in the PixelStore file size. Naturally, if the PixelStore file size is increased in this way, the size of the resulting TIFF export generated from the PixelStore image will be larger as well.

When considering these possibilities, you might check if the pixel size (the size of the area on the ground represented by each pixel in the image) and pixel shape in the exported TIFF is the same as in the source TIFF image.