THING 12: MANAGING IMAGES

Managing images

There are so many different ways to share photos on the web. Some services are focused on organizing and storing your photos, others are primarily social sharing services and others are special purpose sites, like geolocation sites that place your photos on maps.

Digital Tools: These tools emphasize online storage, organizational tools and some social aspects. One of the oldest photo sharing sites is Flickr . Tie-ins with commercial services help you print photos, upside down umbresslcreate photo books and more. Other similar services include: PhotoBucket, Snapfish and Shutterfly. Even Dropbox now has a feature for organizing photo sets for sharing.

Social Tools: With the growth of smartphone & tablet ownership, services that rely on quick uploads from a phone camera and emphasize social sharing have become increasingly popular. Facebook, Instagram, SnapChat and tumblr are all very popular.

Geolocation Tools: Have old photos to share? HistoryPin and What Was There all have interesting map-based sharing features. Build a tour of your town, share historic photos, explore far flung locations.

As well as acting as visual records, images can also be used to create a range of additional forms of data. Advances in computer and camera technology have made many image processing methods more practical and also more economical. Here is an introduction to a variety of image processing techniques that can be used in many different research areas.

Image stitching

The software to stitch images together has been around for over a decade. These images are typically created to either increase the field of view of the image, up to a complete 360×180° view or to greatly increase the resolution of the image, showing extremely fine detail.

3D reconstruction from image slices

There are a wide range of medical imaging devices that can view the internal structures of human bodies and other objects. While the methods of acquiring the images vary, the methods of viewing a 3D representation of the images is the same. A range of software applications are available for processing these images sets for both viewing and creating models for 3D printing.

Photogrammetry

Photogrammetry can now provide high-resolution imagery using relatively cheap cameras and drones that previously required expensive aerial photography or satellite imagery. With a relatively low cost for equipment and software, photogrammetry is increasingly being used for recording significant sites and object. Online services such as Autodesk’s 123D Catch have brought this capability to anyone with a camera but higher quality results can be achieved by running software on your own computer systems.

Reflectance Transformation Imaging (RTI)

RTI is an imaging method that provides a means of inspecting the shape of the surface of an object.

Reflectance Transformation Imaging (RTI)

RTI is an imaging method that provides a means of inspecting the shape of the surface of an object.

Examples to explore:

Image manipulation

There are many tutorials on how to manipulate images both online and in the help files supplied with most image-editing applications.

Here are some of the more commonly misunderstood and/or misused image manipulations.

Sharpening

Many people think that sharpening an image increases the resolution. Most sharpening filters only change the contrast at the boundary of two areas of different intensity (what we see as an edge). This gives the perception of the edge being “sharper” but this does not increase the resolution of the image. Instead it Increases the amount of sharpening a filter performs. Over-sharpening can reduce the image quality by changing the contrast of other parts of the image that are not at the “edge”.

Resizing images

Inserting large images into presentations and documents will not only increase the size of the document unnecessarily, but it may even cause the program to slow down considerably and, in extreme cases, prevent you from saving the document. Images should ideally be resized to fit the intended purpose.

Resizing all of the images within a directory can be done in a number of different ways but the simplest will allow you to specify a specific size to fit the images into rather than specifying the exact size of the images (which may be different). For Photoshop the Image Processor provides a quick method of doing this. Don’t have Photoshop? Mac users can do this with Preview and the freeware application Irfanview is handy for this on Windows.

The following table lists some suggested maximum image sizes. The numbers for publication figures are based on typical journal requirements.

Usage Image size (pixels) Resolution (optional)
PowerPoint slide 1000 x 800 100dpi
Portrait A4 page, Word* 1000 x 1500 150dpi
Single column publication (image only) 1000 (width) 300dpi
Single column publication (image and text labels) 2000 (width) 600dpi
Double  column publication (image only) 2000 (width) 300dpi
Double column publication (image and text labels) 4000 (width) 600dpi

* For general documents in Word, 150dpi is adequate for most uses, which is half of the requirements for image-only publication figures.

Colour ‘correction’

If accurate colour is critical to your images, then you will need to calibrate your image capture processes to achieve this. Correcting colour manually is fraught with danger because one of the most powerful image processors is not connected to the computer. The human brain can process images very rapidly and the interpretation of colour is based in part on context of the image. These optical illusions demonstrate how easily our brain is fooled.

As if that’s not enough, our built-in image processors are all different, and slightly flawed to varying degrees.  Try taking this simple test to see how well you can pick differences between colours. So while it may be okay to adjust the appearance of an image to make it look “nice”, if the accuracy of the colour is important then it’s not so much a question of “how do I adjust the colour?” but “should I adjust the colour?”

Nearly all image editing applications have some form of automatic colour correction and most of these make use of two things:

  1. the assumption that every image has a small percentage of both black and white in the image.
  2. the principle that colour correction is the process of changing the numerical values of a colour to the known values for that particular colour.

This works pretty well for improving the appearance of most images but in some cases the first point may not apply to an image, causing the correction to make the image look worse. This Photoshop tutorial outlines a manual process that provides more control using the same two principles. Equivalent steps can be found in most other image editors.

More information:

Colour calibration

The best way to get accurate colour images is, obviously, to get it right the first time. There are a range of calibration targets and software that make it possible to get accurate colour from scanners and cameras without requiring manual correction later.

More information:

Metadata

Having metadata means you can easily search for and find pictures as your archive grows. It also means that you can store details within the images, and refresh your memory about them should you need to later.  Embedding metadata into images is one of the most important “manipulations” as it provides invaluable context for the image.

On the surface, though you could be forgiven for thinking that it’s really difficult:

  • There are two ways in which metadata can be embedded into an image: Information Interchange Model (IIM) and Extensible Metadata Platform (XMP). It is possible for an image to have both at the same time, with different information in each. For simplicity we’ll ignore IIM for now but be aware that it exists.
  • There are several different namespaces that can be included within XMP metadata. Their usage and interpretation is inconsistent between applications, e.g. Dublin Core (DC simple), International Press Telecommunications Council (IPTC), Publishing Requirements for Industry Standard Metadata (PRISM), Creative Commons (CC) to name but a few
  • Camera and scanner manufacturers enter product information into images in many different ways, occasionally misusing fields such as creator and description.
  • Large companies dealing with images occasionally go off and create a metadata schema for their own purposes

There have been a number of initiatives to try and promote the use and consistency of embedded metadata such as IPTC’s Embedded Metadata Manifesto and the industry led Metadata Working Group but a number of challenges remain for it to be a common practise. Possibly the greatest challenges stem from the fact that there are very few software tools for embedding and updating metadata, especially when it comes to handling large numbers of images. While embedding metadata is a technically straightforward process, tools to allow for updating several metadata fields in several images efficiently have not really been produced for mainstream use.

The inclusion of metadata in images allows it to be reused in other application. Many web hosting systems will automatically populate fields from the metadata in an image, making it simpler to upload and share large numbers of images without having to do additional data entry. One important thing to be aware of when using third-party image sharing sites, is that while they may add your metadata to the page displaying the image, it may not be present in the images people download.

Returning to the “images as data theme”, the use of metadata in scientific imaging systems is used to provide information about the various settings of the equipment used and the conditions under which the image was produced. In this case there are a large number of tools for specific applications to deal with the variety of data specific to each discipline. Packaging the data within the file makes it easier to share the images whilst still providing the information required to interpret the image and make valid comparisons with images from other sources.

In many cases a lot of scientific “image formats” consist of a standard file format such as TIFF with a custom metadata schema added. The Open Microscopy Environment (OME) TIFF specification, for example, is essentially an ordinary TIFF file with XML metadata added into the standard description field.

Metadata is critical for finding images easily, but in order to save time you have to spend the time creating good quality metadata. Doing this efficiently is certainly challenging but is well worth the effort of learning create it.


Try this

If you’ve already joined a photosharing site and are ready to explore some more, here are some ideas!

  • Test out an editing tool that you haven’t used before.
    • Join a photo challenge – FatMumSlim photo-a-day is a popular and fun one. You don’t have to do a whole month. Try it for a week!
    • Create a collage and post it to your blog.
    • Explore Big Huge Labs and make something fun. A magazine cover, a Trading Card or…
    • Create a slideshow to put on your website or blog.
    • Try out some new photo editing apps on your smartphone or tablet.

Explore further

In the commercial world time is money. Streamlining the management of digital assets including images is a business improvement. Examine some of the challenges outlined in white papers from commercial digital asset management solutions such as:

Photo Editing– try your hand at editing a photo using one of these web and/or app photo editors.

Photo Fun– Make posters, slide shows, collages and so much more. Lots of interesting ideas here.

Share your experiences and problems with others. Leave a comment with an example of your own challenges or share via a blog post.

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