Resize digital images

A number of our members are new to computers and have experienced difficulty in resizing their images correctly for submission to club competitions and evaluation evenings.  This guide leads you through the resizing and saving process and if followed will ensure that your images are optimally sized for display and are also not so large as to waste bandwidth when being e-mailed.  This guide assumes that Adobe Photoshop is being used and screen shots were made from Photoshop Elements 7.  However the steps are likely to be similar in other image editors.

After you have finished processing your digital image, scanned slide or scanned negative you must ensure that you save the full sized image.  If you have used layers then you should save the file in TIFF or Photoshop’s native PSD format to ensure that you can go back to refine your processing in future. Only once you have safely saved your image should you continue with the resizing steps.  We will begin with your full sized image open in Photoshop.

The first step is to resize the image itself.  We do this using the Image|Resize|Image Size… command on the menu or by pressing the keyboard shortcut Alt+Ctrl+I (Opt+Cmd+I on a Mac).



This will open the Image Size dialog.  There are a number of settings that we need to check here.  Resample Image must be checked and the resampling mode set to Bicubic Sharper.  Constrain Proportions must be checked and if your image has any layers with styles applied then Scale Styles must also be checked.  We are simply going to change the pixel dimensions; if your image has a horizontal format then type 1920 into the Width field, ensuring that pixels are selected in the field alongside.  If your image has a vertical or square format then type 1080 into the Height field instead, again ensuring that pixels are selected in the field alongside.


In the image above I have typed 1920 into the width but, due to the aspect ratio of my image (3:2) differing from that of the projector (16:9), this has resulted in the height changing to 1280, larger than the maximum of 1080. It is important to check for this and if it happens, you should should adjust accordingly so that both height and width are no larger than the allowed maximums of 1920 for width and 1080 for height. So for this image I must type 1080 into width instead. This gives me the largest possible image with a 3:2 aspect ratio that can fit into the 1920×1080 16:9 aspect ratio display of the projector.



Click OK and your image will be resized to the best possible size for display on the club’s projector.

Next you are going to save your image in JPEG format, ensuring that the file size conforms to the club’s requirement that image files are no more than 1MB in size.  To do this select File|Save As… or press Shift+Ctrl+S (Shift+Cmd+S on a Mac) to open the Save As dialog.

Save As (49)


In this dialog made sure that the Format is set to JPEG (*.JPG;*.JPEG;*.JPE) and type your file name into the File Name field.  It is not necessary to type in the extension (.jpg) as this will be added for you.  Remember to name the file according to the naming guidelines; S, O or E, followed by a 1 or 2, then your name and the title of the image.  Each section should be separated by an underscore (_) character.  For example, O1_Steve Crane_Beach Decay.

Ensure that the ICC Profile option in the Color section is checked and that an sRGB profile is being applied.  If not, cancel the Save As… dialog and select the appropriate sRGB profile for your image before doing the save as again. In Photoshop Elements 7, the menu options to do this are Image | Convert Color Profile | Apply sRGB Profile.

Once you have the correct name and profile option in the Save As… dialog, click OK and you will be presented with the JPEG Options dialog.  Our aim with this dialog is to use the best quality (least compression) we can while making sure that the image size is under 1MB.



You do this by first moving the quality slider all the way to the right setting the quality to 12.  The estimated file size will be recalculated and will probably be larger than required.  Now move the slider slowly left until the quality changes to 11.  Allow the estimated size a moment to recalculate and see if it is still above 1MB. If you don’t see the estimated file size, make sure that Preview is checked. If the size is still above 1MB repeat by moving the slider until quality is 10 and so on. In the example above, I started at 12 resulting in an estimated file size of 1.4MB and selecting 11 changed this to 848.5K, making the image smaller than the 1MB limit.

As long as the quality remains at 7 or above your image will display fine on the projector. If the quality is at 7 and the estimated file size is still larger than 1MB then you need to repeat the resizing step as the image contains too much detail to compress sufficiently without too much degradation in quality.  In this case you should click Cancel and repeat the resizing step using smaller values than 1920 and 1080 before trying to save again. Try not to make the image too small; sizes below 1024×768 will seem tiny when displayed by the projector.

Once you have resized and saved all the files you wish to submit, simply attach them to the e-mail but be careful when doing so.  Some mail clients will offer to make the images smaller, suggesting that smaller files are more e-mail friendly.  While this is true, these mail clients do not take into account that you are not trying to send full resolution photos and have already resized them as you want.  You must therefore answer carefully and not allow your mail client to resize the images.

%d bloggers like this: