How To Deal With The Problem Of Emails With Large Files

An artist contacted us at Flying Twigs recently. She sent me a bunch of images and asked for my feedback asking whether her style and our cards would be a good fit.

Here’s a tip for artists and illustrators who want to put their work in front of a potential audience: It’s better not to email a bunch of big images to a prospect.

That’s because it’s not a good idea to fill up the recipient’s email space with 50 Megabytes or more of email attachments.

So, with that in mind I gave some feedback to the artist who emailed me.

I noticed that she emailed a lot of people at the same time and I gave her a ‘heads up’ about large email enclosures and how to deal with that in future in case she didn’t know how to do it.

She took my reply in good part and asked how to do it and I decided to put my reply in a more visual form and turn it into this ‘howto’ article.

Before I go into some solutions for reducing file sizes, a word about kilobytes and megabytes.


I have the full-size original version of this image on my computer. I took the photograph and then did some work on it with Photoshop. I saved it as a JPEG and the size of the file is 14.59MB.

The size of the image is 4551×3264 pixels because that is the number of pixels on the camera I used to take the photo.

The version of the image you can see here isn’t full size.

It is just 600x430px.

Here is the area of this smaller-size image – shown by the green rectangle – compared to the size of the original image. It is about 1/40th of the area of the original.


However, not only is it a smaller area, because of the way I saved it with Photoshop’s ‘Save for Web’ capability, it has also been scaled to render on the screen at less pixel density than the original, and the size of the file is just 48 kilobytes (48KB).

That is 48KB compared to the original file size of 14.59MB.

That is less than 1/300th the file size of the original image and yet it is perfectly viewable on the screen.

It has smaller pixel dimensions, true, but then we don’t need an image that is 4551pixels wide if we only have a computer screen to show it on.

Here are some Photoshop screen grabs to show you a bit more about what I mean.

In this first shot you can see the 600pixel-wide image at 100%


In this second shot you can see the full-size image at 100%


You see I really don’t need the full-size image if I am viewing it on a computer screen. At least I don’t need the full-size image unless I want to look over every inch of the image in great detail.

How Much Compression Is Enough and How Much Is Too Much

I saved the 600x430px image at 40% compression. If I had saved it at 100% – i.e. no compression at all – then it would have been 280KB. That’s bigger than the 48KB version but it’s still a lot smaller than the huge 14.59MB of the original.

JPEGs are a lossy format. That means they compress the size of images by enabling the pixels to cleverly scan the pixels next them, and if they are the same hue, then to combine them when the file is saved.

When I save with more compression, (e.g. 40% rather than the no-compression 100%) then the pixels read several pixels around them and average out the result.

In other words, the more compression the less the resulting compressed image is faithful to the original.

That’s why I rarely compress to more than 40%.

OK, so what we have established now is that if I am sending images by email I can send small images.

Now I might want to send an image that is more that 600pixels wide. And with Photoshop or Lightroom I can choose any pixel dimensions I want.

I might choose 1,000pixels wide for a bigger image – but still one that is compressed for viewing on the screen.

Tools To Resize Images

If you don’t have Photoshop or Lightroom, you can search with Google for image-compression tools. One that I checked out and like is Image Optimizer.

You can use it online or you can download the app. And you can choose the width of the resulting image.

Let me know how it works out for you, or any other tools you use for compressing images.

29 thoughts on “How To Deal With The Problem Of Emails With Large Files

  1. Thanks to you and Cardinal Guzman I now always resize and compress. I don’t want to fill up my quota here in WordPress.

    I honestly don’t know why Photoshop will let go of Save for Web. For the moment it’s hidden deeper in the menu than it was before and says (Legacy).


  2. Great article. Remember the first thing you taught me was this very conundrum of image sizes? But the balloon analogy is missing in the article. That explains better to lay man.
    In Linux File Managers, there is a plugin like image resize and file size can be reduced by one click in context menu. For example install converter with command “sudo apt-get install caja-image-converter”. In linux Mint, Caja is the default file manager. Such converters are available for other file managers as well.


  3. Pingback: Useful tips for artists and illustrators | one cool site

  4. I somehow missed this when you posted it. Luckily Timethief decided to share it 🙂 You’ve created my new go-to resource for explaining image optimisation to people.

    Another great tool to save space with image files is . You use it after you’ve resized and edited and compressed. I’ve had it reduce a JPEG’s file size by almost 50%, without any noticeable loss of quality. (@justjennifer put this one on my radar.)


  5. Timethief sent me in this direction. I have a lot to learn, and this question may show my ignorance: if I set my camera to take shots 640 pixels wide, because that is the size of my column width, do I not need to be concerned with resizing/compressing/optimizing my images? Also, by taking photos that are only 640 pixels wide, am I getting poor detail, and would be better off taking photos, say 1200 pixels wide, and then resizing? Thanks.


    • That’s an interesting question. I have never owned a camera where I can set the pixel size. I think your camera must be designed for uploading to the Web. It’s easy to test. Upload an image and look in the WordPress admin page at the file size as you do it.
      To answer your other question, again I can’t be sure because I don’t have a camera that does this, but my guess is that if you take a shot with a small pixel size then you are not going to have a full-size image.


  6. Good job of explaining the what and why of resizing images.
    I use the Faststone Image Viewer to do the job. It is freeware, and I can batch convert a group of images, resize them, add my copyright text, and a border all in one go. Faststone can also losslessly rotate JPEG files.


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