Common Digital Photo Problems and What to Do About Them
Digital photographs need to be handled carefully to ensure that photo problems are not created during image editing and image processing.
Making sure that your images and photographs look their best is very important. You will not impress your customers with blurred or blocky images.
There are a number of digital photo problems which you may come across. Here are a few which you should be aware of and know how to avoid.
Why is my photograph blurred?
Sometimes when images are printed or placed on a website they can look blurred and fuzzy, rather than sharp and crisp. There are few reasons why this can happen. Some are easy to fix; some not so easy.
Here are a few possible reasons for blurred images:
- Image size is too small – not enough pixels.
- The image has been been resized down from a very large image to a very small image in one jump (and has thrown away too much image information in the process).
- The image has been enlarged from a small image to a much larger image (adding in information which wasn’t originally there).
- The original photograph was blurred when it was taken – check the original file from your camera.
If the original image from the camera is blurred, it may be due to camera movement or subject movement, or blurred images can be caused by focussing problems at the time the photograph was taken.
It may be possible to sharpen an image with image editing software such as Photoshop. However there are limits, and if the original photograph is very blurred it may not be possible to fix it.
If the original photograph seems OK, then it may be a problem with the resizing process or other image editing which you have done. If this is the case you should go back to your original photo file from the camera and try again.
Note.
Never save over your original photograph files after doing image editing or resizing, as you will then have nothing to go back to if you find later that you have made a mistake.
Always save the edited image as a new file with a new file name, and keep an un-edited copy of the photograph somewhere safe until you are certain you don’t need it.
Please see this page for more information on image size and image resolution and resizing photographs and images for print and websites.
Why is my image blocky?
Blocky images or pixelated images are often caused by the image being too small or by being saved as a low quality JPG file. If the image is very small you may be seeing individual pixels.
If the image is large enough it is probably caused by applying too much compression to a JPG image file – or saving as a JPG multiple times.
Why does my image have jagged edges?
Jagged edges – usually along contrasting lines (such black / white edge areas) can be caused by problems with image resolution, or by incorrect image processing.
Here are a few possible reasons for jagged edges in images:
- Low resolution image – the contrasting edges will often look jagged if you zoom in to the image on a screen.
- Over-sharpening the image with the sharpen tools and filters.
- Saving the image as a JPG file (especially if re-saved as a JPG multiple times).
What is JPG damage?
JPG damage is the damage cased to images when they are saved as JPG – usually as result of saving a low quality/high compression jpg, or re-saving over the jpg file multiple times.
JPG damage typically appears as a blocky pattern where there should be smooth colour. It is often particularly noticeable on areas of sky.
What are JPG artefacts?
JPG artefacts are block patterns and rippling edges which can appear when an image is saved with JPG compression.
JPG image format – Good or Bad?
JPG files are very useful in situations where the file size needs to be as small as possible, such as when saving images for web sites or email.
However saving images with JPG compression can cause significant damage to the image quality if not used carefully.
Most digital cameras save photographs as JPG, and the image quality can be acceptable if the camera is set to save with the highest quality/lowest compression (the exact options will vary for different makes of camera). Many professional and semi-pro cameras can also save as Tiff or Raw format, but these create much larger files than the JPG file size.
JPG compression makes images file sizes smaller by throwing away a certain amount of image information.
The amount of image information that is lost is determined by the quality/compression settings when saving the JPG file.
The higher the compression, the lower the image quality and the smaller the file size – but more image information is lost.
JPG compression is known as lossy compression.
This lossy compression is a particular problem if an image is re-saved as a JPG a number of times. Smaller images with high compression (e.g. images optimised for websites) are most likely to show obvious damage.
JPG quality settings and image quality
High Quality JPG = low compression = larger file size = less images on the disk or memory card.
Low Quality JPG = high compression = small file size = more images on the disk or memory card.
So it is a balance between image quality and file size.
In Photoshop, a JPG quality setting of 60 – 70 is ideal for good quality images for websites. For a higher quality image – maybe for printing – you might choose a quality setting of 90 or even 100.
Saving JPG files without damaging your images
Only save as a JPG once
If you are editing an image and want to be able to re-save the image at intervals, you should only save as a non-lossy file format such as TIFF or PSD, and the save a copy or export the final image as a JPG when you are finished editing.
If you need to do more editing, edit your source image (the one saved as a non-lossy image file) and again save or export another JPG file when the editing is complete.
Save high quality JPG files
Use high quality / low compression settings when saving a JPG to minimise the compression damage.