Limit Number of Images in Upload

Perhaps your theme is registering additional image sizes. Check your functions.php file

The default twentyeleven theme registers additional image sizes for custom headers. Effectively for header image:
set_post_thumbnail_size(1000, 288);

Custom image sizes effectively
add_imagesize(‘large-feature’, 1000, 288);
add_imagesize(‘small-feature’, 500, 300);

I’m assuming here that because the images that I am submitting are over the width and height of the custom header image, that the behavior of the uploader is to take any images over that size and apply all the image sizes registered, thus causing additional files.

The problem here is that the large-feature and small-feature properties are not being shown in the media settings. If it were, I could disable the rendering of those images by ticking off or setting to 0 the width and heights to avoid generating the files.

Switching to another theme.

Just switched to Suffusion theme.

This thing creates

24×24
36×36
48×48
64×64
96×96
150×150
300×169
1024×577

About 350K of total file size from an original 180K PNG file.

This theme too, doesn’t show any of its file size settings on the media settings panel.

Users should be able to control and select the image file sizes. The image descriptions (i.e. large-image) should have a description next to it to tell the admin what types of images belong to that category along whether it is optional or necessary. That way we can reduce the amount of disk space being used and reduce the amount of files to search through the media manager (which is useless because of horrible categorization facilities).

Most themes do not show image sizes as an adjustable option in the admin – as they are usually critical to proper functioning of the theme, plus users can easily control the core sizes to their liking via Settings > Media as you noted.

You can edit the add_imagesize functions out of your theme to prevent those sizes from being registered and created.