Over the last number of weeks, DigiKnow has written a number of blogs on different photography elements: composition and automatic mode, Program Mode: exposure compensation and white balance, depth of field and aperture, shutter speeds (aperture/shutter relationship) and a number of shutter speed techniques: zoom burst and painting with light, ghosting and multiple-exposure, panning and blurring moving subjects.

This week, DigiKnow moves on to the basic editing of images via Photoshop. It doesn’t matter if the image to be edited is from a camera, a phone, a screenshot, etc., it can be edited in editing software that supports or opens certain file types.

If images are from the internet, do review Terms and Conditions regards Copyright and/or Creative Commons. Just because something is available on the internet doesn’t mean it can be used. You may need to seek permission.

If purchasing images, check Terms and Conditions of where these images can be used and if they can be edited.

Let’s have a look at the most commonly used file types.

File types

Image file types that are universal include JPG, PNG, TIFF and GIF. Each file type has it’s own pros and cons.

Typically, JPG or JPEG (Joint Photographers Expert Group) is a digital (raster) image in a ‘lossy’ format. By ‘lossy’, it relates to file compression. When a JPG is saved, users are prompted to choose a ‘quality option’, the lower the quality option selected results in more compression used in the output. Higher quality options use less compression, resulting in a better quality image.

PNG (Portable Network Graphic) supports transparency and PNGs are heavily used in website design, video, animation, etc. The format is lossy, but ideal for diagrams and images with a limited palette of colours, such as charts and screenshots from phones and computers, as it can reduce images with large areas of the same colour to a very small filesize, with no visual loss of quality.

TIFF (Tagged Image File Format) is a raster format popular among graphic artists, photographers and the publishing industry. It’s a ‘loss-less’ format which means when TIFFs are saved, they don’t compress the information and file sizes are large.

GIF (Graphic Interchange Format). These are loop animated images (without sound) and are popular in website design and used on social media. GIFs use several images within the same file and can support transparency. They work on the majority of browsers and devices.

Not all these file types will be used by everyone, however, they get mentioned here as being the most popular image formats encountered.


When it comes to resolution, there are several things to consider. Screens on every device has a resolution. It’s the total number of pixels a screen can display, i.e., 1920×1080, 1280×780, etc., the larger the screen, the larger the numbers and the better the resolution.

Despite screen size, resolution in camera terms is the total number of pixels that create the image, for example, a 16MP camera can output images with pixel dimensions in the region of 4928×3264. When these two numbers are multiplied, it gives the number of megapixels of the camera. Smart phone cameras can range from 8MP to 40MP and the more MPs available are larger file sizes.

If an image has resolution, it’s a solid (or raster) graphic. For example, every pixel has an x-location, y-location and a colour value assigned to it. When the pixels are viewed on a screen, the total of pixels make up the image. Below, you can see a magnified section of an image which demonstrates pixels within a grid.

Credit: Daria Casement
Credit: Daria Casement
Image quality and output

When creating/editing images, consider what they are for. Are they to appear on the internet or in a publication? Are they for presentation or photographic purposes? What size do they need to be and why is this important?

Once you have the height and width an image needs to be, consider where the image is to appear. Below is a list of outputs and pixels per inch (ppi) for those outputs:

  • Internet/social media – 72ppi
  • Newspaper – 200ppi
  • Magazine/Photographs – 300ppi

Publications and journals will have their own image specifications, colour spaces and file types. Read individual specifications in this instance.

The file types listed above are the most used universal formats. If you’re not sure, JPG is a reasonably safe bet as an output type. Just remember that JPG is a ‘lossy’ format and to use the highest quality when saving to reduce the amount of compression on the image.

Colour modes

There are a number of colour modes available from RGB (Red, Green, Blue with 16,777,216 colours), Indexed colour (with 255 colours), Grayscale (with 255 tones), CMYK (Cyan, Magenta, Yellow and Black) and Bitmap.

With today’s internet speeds, RBG is a good colour mode to stick with. If the output is printed, this may need reviewed, check specifications.

Photoshop – basic editing

Moving on to getting familiar with Photoshop, below you will find the Photoshop environment for Photoshop CC 2020 below. This has been sectioned off with numbers.

Photoshop Environment
  • Number 1 – Tool bar
  • Number 2 – Options bar
  • Number 3 – Panels
Tool Bar
Tool bar
Tool bar

This consists of twenty-two tool buttons. Many buttons have multiple tool sets within them. View the tool bar, any button that has a triangle at the bottom right of the button, this indicates multiple tools are available on this button. Click and hold the mouse on any of these buttons to view other available tools.

So although twenty-two tools are on display, there are upwards of fifty available tools in total. This number is always increasing. However, only one tool can be active at any point in time.

By categorizing tools within the tool bar, there are a set of tools for:

  • Selection
  • Brushes
  • Vectors, and
  • Navigation

Also note colour control options toward the bottom of the tool bar.

Options Bar

This is situated just beneath the Menu Bar.

Option bar (Marquee Tool)
Option bar (Marquee Tool)

The Options Bar changes depending on which tool is currently selected and it allows the user to configure the tool currently in use.

If that’s a brush, the user can change the size of the brush, the shape of the brush, whether the edge of the brush is hard or soft, how the paint flows off the brush, etc.


These appear on the right hand side of the screen. As a novice user of Photoshop, the following palettes are helpful:

  • Navigation
  • Colour
  • Layers
  • History

If a number of images are open, panels hold information on the image that is currently in use.


To crop an image, click on the Crop tool on the tool bar.

Crop tool
Crop tool

A ‘free size’ crop can be selected or the crop selection can be restricted to a ratio or a pre-defined number of pixels height and/or width. Ratios and height/width would be input to the Options bar in that instance.

Crop Options bar
Crop Options bar

By clicking the drop down on W x H x Resolution, options include:

Crop dimensions
Crop dimensions

NB: if using the Crop tool and the selection is restricted to a ratio/pre-defined size, click Clear on the Options bar to all free size selections.

Remember to press Return/Enter or choose the Check Mark in the Options bar to confirm the crop. To cancel, press the Esc button.


To straighten images, this can be done via the Crop tool in the tool bar. Make a crop selection, move the cursor beyond the selection bounding box and the cursor icon changes to show a bent double-arrowhead. This allows the user to rotate the crop selection to straighten an image.

Crop tool - Straightening an image
Crop tool – Straightening an image

Remember to press Return/Enter or choose the Check Mark in the Options bar to confirm the straighten. To cancel, press the Esc button.

Colour fixing

In this post, we will cover the ‘Auto’ colour features. Basic colour corrections.

Auto colour features to correct Tone, Contrast and Colour are under the Image Menu. Anything relating to colour correction/enhancement in Photoshop is under the ‘Image’ and ‘Adjustment’ Menu.

Image menu
Image menu

NB: In older versions, all colour options were under ‘Image’ and ‘Adjustment’ menu, including the Auto features.

When an image is open in Photoshop, menu options become available. If you have an image open and go to the Image menu and click Auto Tone. The image might change slightly or drastically. This depend on the image corrections needed and calculations done by Photoshop.

To remove an action (an action is defined as something you have just done, i.e., applied Auto Tone), it can be removed by going to the Edit menu and Step Backward.

Auto Contrast and/or Auto Colour can then be applied. It’s best to view each feature individually. Sometimes the Auto features will be subtle, other times, dramatic. It depends on the image starting point and how well captured the image is.


When it comes to saving the images you have been editing, it’s best to use File and Save As. This gives the opportunity to save the worked image to a different folder and give it a meaningful name (i.e., it may be placed in a Photo folder, a Publication folder or Project folder with a relevant file name).

If saving photographic quality images, these should be 300ppi and can result in quite large file sizes. Ensure the quality setting is 12 (least compression) and it should then be ready for photographic printing.

The photographic file in a presentation would be bigger than the slide on display. It’s best to resize the image to be slide sized (i.e., slide height and width). This not only helps when inserting images, it also cuts down on large file sizes of presentations.

Think before you post images on the internet. Even with Copyright symbols, one can lose control of where an image appears due to copyright infringement. Read through the Copyright and Creative Commons posts.


This week, DigiKnow has provided the basics for image file types, resolution, output considerations and basic editing techniques in Photoshop. These editing techniques are transferable to other editing packages. Check out online tutorials for other editing packages.

Next week

We intend to build upon the editing techniques in Photoshop regards colour correction/enhancements, cleaning images and layers. Join us next week to learn more.

Don’t forget to join us on twitter: @MDBSelearn.


Leave a Reply

Avatar placeholder

Your email address will not be published.