Resize & Reformat Images in Bulk
Tools to work with images for free and premium
Resize & Reformat Images in Bulk
JD Berkowitz 29 December, 2021
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If you are looking to resize, reformat, convert or watermark your images you have numerous options nowadays but finding the right one for your use case may be a challenge. Here is a short list on some useful resources for working with digital images.

The Problem

If you work on the web then you are all to familiar with the struggle for the best way to manage your images. I work with several large catalog ecommerce clients and we are constantly struggling to balance cost, time and frustration when dealing with our image assets from our suppliers. 

Often I find images are incorrectly referenced in the data file (spreadsheet) leading to import errors and time lost correcting trivial mistakes. This can amount to a significant amount of overhead just for maintaining data on the vendor and client sides. However, if we use the right tools we can greatly reduce errors and friction in our data setup process. 

We can fix this be standardizing our delivery of image assets through an API, PIM or ERP. If done correctly you can save an enormous amount of overhead for your operation. But this takes technical and intimate industry knowledge to do successfully. If you are interested in learning about how I can help in such situations feel free to send me a message via chat below!

Tools for Image Manipulation

If you spend some time Googling some solutions you will find many online and offline options for manipulating images but here I am going to focus on resizing and converting types as well as look at some solutions we can learn on the desktop and deploy to cloud functions in order to automate bulk processing and offload required resources so we don't tie up our own machines!

1) Adobe Spark Express

First off if you are just looking to resize or convert a single image then tryout this free tool from Adobe called Spark. You can export to templates for a variety of platforms. Spark is powered by Photoshop but offers a learner more user friendly way of interacting with your media.

2) Adobe Photoshop 

If you have an Adobe subscription you can always use Photoshop to crop and convert your images. Batch processing can be done on entire folders with Actions by recording your process. It is fairly simple but requires a Photoshop subscription and can tie up your machine for a while so if you are trying to multi-task it can make your life a challenge.

3) Easy Thumbnails

This is a little piece of free desktop software for Windows that is still one of my favs for quickly renaming batches or images or resizing them. It is super easy to use and rather fast. It is super lightweight making it easy to run alongside other processes however it will slow down the conversion process if you continue to use other apps.

4) ImageMagick Bulk Image Processing

This is my favorite tool as it is super fast, easy to use from the command line, and can be run on a VM in the cloud to offload image processing tasks once i am certain i know the workflow I would like to implement. It is worth mentioning that many of the online and in app tools will use this library to process the conversion. It is available for Mac, Linux and Windows as self installing binaries so it is as simple as clicking install!

The amount of memory can be an important factor, especially if you intend to work on large images. A minimum of 512 MB of RAM is recommended, but the more RAM the better! I can run this just fine on my laptop with 16GB RAM and even better on my desktop with 32GB. Your CPU will matter a bit as well, my 2 core laptop is significantly slower than my 8 core desktop.

Let's take a look at how we can install and use ImageMagicK to resize and convert our product images into a smaller size and standard format. 

1) Install ImageMagicK

Head over to the open source page here and find your operating system and download link.

I will be installing the windows version that is prebuilt with some common options.

Follow the prompts to finish the installation.


2) Add all the images you want to a folder. Anywhere is fine.

I chose some large files, some medium size files and both jpg and png to show how the conversion works but normally I am processing thousands of product or lifestyle images.


3) Press your Windows key and type "cmd" then click "Run as Administrator"


4) Copy the path of your images folder by highlighting the folder URL and pressing Ctrl+C (or right click and copy)


5) In the command window type "cd " (for change directory) and right click to paste the folder address. The press Enter. 

So it should look like this.


6) Resize your images to a fixed size.

Run the command below to resize your all your images (*.*) to 1024x1024.

Change the dimensions to your desired value and you can change the selector to process only select types of files. For example you can use *.jpg or *.png to select their respective types.

It will  resize to fit the frame siz eyou provide so if the image is smaller nothing will happen.  If it is a different aspect ratio than you define it will use the longest size and fit the image in without stretching. 

magick mogrify -resize 1024x1024 *.*


7) And/or convert from PNG to JPG you can use the command 

magick mogrify -format jpg *.png


The "mogrify" command will overwrite the current contents of the folder but if you want copies to be made you can use convert command. See the documentation here for examples and instructions.

In a future article I will explain how we can move the process from our desktop to a server in the cloud and trigger it when we upload images to our repository. In the meantime I hope you found this useful and if you want to learn more drop me a note in the comments below!


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