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Bit Image

From ceramic production to pottery we need to take photos, knowing something about the file formats and working with them saves money, time, the environment.


Digital photographs are "bit images". Ceramic artists and technicians must deal with them constantly, knowing something about the subject is valuable. A bit image exists as a file on your computer or on a server on the internet. Bit images are a matrix of tiny dots (pixels) each having a color and transparency. The image as a whole has "dimensions", a 1000x1000 dot image thus has one million dots. For print purposes, a image as a whole can also have an implicit dpi "resolution" (dots per inch). The 1000x1000 dot image can be said to have a resolution of 100 dpi at 10 inches or 200 dpi at 5 inches size. Obviously, storing information on every single pixel is going to take significant memory (on your computer or in the cloud). The capicity of computers to deal with billions of pixels in an instant is a testament to their speed.

Image files have a "format", a way of encoding the pixels. Formats have advantages and disadvantages. Common formats are jpg, gif and png. GIF limits the number of colors to 256 (to reduce file size) but it does have an animation capability. PNG saves all pixels as-as, JPG groups pixels and compromises the colors of some to create patterns that enable reduction in file size (thus each time a JPG is saved some quality is lost). PNG and GIF pictures can have transparency.

Almost any photo you take needs to be edited. Cropping is typically the first thing done. While photo editing software like GIMP and PhotoShop are well known, computers and phones have photo editing capbilities built in. These can typically save to other formats. However computer vendors (who also market cloud storage) have an interest in keeping your photos in the largest file size possible. For this reason is it good to use a third party app that enables resolution and degree-of-compression control.

Every time you upload a photo to the cloud you impact the environment (by the size of the file). How? Data warehouses that store all this stuff are the size of shopping malls fed with electrical cables the size of a firehose! Dozens of nuclear power plants are needed to run all that. So think about resolution and image compression.

What resolution is right? As a guide, consider the resolution of your computer's monitor, your phone's screen. HD monitors are 2000 pixels wide. Phones are commonly that height. A 4k photo would be twice as wide and more than twice as tall, that means it is four times the needed size. While the larger image would permit zoom, consider the extra time to load it. Better to crop the original image before upload. In that way its actual size on the screen will enable quicker viewing (and faster display).

What compression is right? When JPG images are saved a compression percentage can be specified. Higher ones take more space. Really high (e.g. 85% or more) can take dramatically more space. Compare results to see what is best, typically 70% is fine. Consider a best case scenario: Your camera produces a poorly focussed 4000x4000 image of 5mb in size. You edit that image in a photo editor, cropping it and reducing the resolution to 1600px wide (which sharpens it) and save it as a JPG image with 70% quality. That saved image could easily be 250k in size, 20 times smaller (and it looks better).

Related Information

Cutting out the background on a photo

White backgrounds are used for presentation on ecommerce websites (contextual backgrounds when showing a product in use). Even if you can photograph to pure white at the edges of a photo, it will transition to grey around the object and pieces will almost always have some fuzzy edges. While there are automated edge-detection tools in editors like Photoshop or GIMP, they do not give clean edges like this. So professionals do this job using a vector-editing tool. In the past this implied learning the path tool (e.g. inPhotoshop) but now inexpensive phone apps can do it well. On the lower left is the original image (already cropped). On the lower right I have it open in an iOS app named Exacto. The blue dots are stationary anchors and the black ones pull out curves between them (curves flow smoothly through the black ones). By zooming and add/moving dots I can produce these crisp edges (Exacto saves it to iOS Photos with a transparent background). Notice how clearly the clean edges enhance the throwing rings on the right.

Same photo on my Nikon D-3500 and iPhone 8

The camera shot (top) is higher resolution, but not alot. Focus on the edges is better but I it could still be improved.
But the iPhone colors are more vibrant. On the camera-shot the red, orange and yellow are washed out against the white background. Surfaces are softer on the camera-shot. I am guessing that as I learn to use the camera better it will improve. An aspect of the camera is that the screen does not have the quality the iPhone has so it is more difficult to tell if it is adjusted and focussed right.

Using a camera instead of a phone for your picture taking? Beware

Taking a picture on a modern smart phone is easy. And you can just walk over to your desktop computer and it is there automatically (e.g. for editing and uploading to your account at Cameras are capable of taking better pictures, but time and dedication are required. But don't overlook the difficultly of getting photos from your camera to your desktop computer. Camera software (to transfer the data, edit photos, store and share them) is not nearly as polished a phone apps. Transfer can be awkward and glacial (e.g. 10 minutes per photo!). If you already have a camera and this is an issue, consider getting one of these SD cards (e.g. on Amazon). This turns your camera into a router/website that you access by switching your wifi to it. And transfer is fast.

By Tony Hansen

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