The Algorithmia website offers free online auto black and white photo coloring online using an automated algorithm.
If you have old black and white photos of your grandparents, then it is worth trying the Algorithm website. You will find a free, online service that uses an algorithm capable of adding color to black and white images. The way of use is very easy. Paste a URL in the box or upload an image, wait for some time to complete the edit, and you will see the colored result.
The service displays a comparative image with half being the original black and white and the other half colored. Drag the vertical purple line to display more or less colored parts of the image to see how it will look before you download it.
The processed images can be downloaded either as a comparative image or as a full color image. Both features will have a watermark at the bottom right edge. Downloading the comparison image will display the image with the purple line. Move the purple line before downloading the comparative image to get the coverage percentage you want. The default is half the original image and half the color image.
The service is not perfect and can produce some interesting and unusual results. Sometimes it takes a little while to process the images, It can even reach 15 seconds. Although it always depends on your internet connection.
Overall results tend to be sepia - yellow, especially when the algorithm does not recognize anything. Of course it is not a serious tool for coloring images, such as what you will find in an advanced graphics program. There are no options to make adjustments to the colors or areas of the image, but it's a fun tool that will not get you tired and the results often look good.
There is an interesting note from Algorithm, where it says that the service will color on either side of the image or the other, depending on the browser you are using. Firefox-based browsers have the colored effect on the left side of the image. Chromium-based browsers show the color effects of the image on the right.
You can try out any of the five sample images to see how the service works before you pick up one of your own images.