How to Resize Image by File Size

[Neil Pho]

I am looking for a lightweight tool for resizing images by file size. Ideally I would like to be looking at a folder in Windows Explorer, right click on an image and choose "Resize". Then enter a value like "500k" and end up with a scaled image file with a name that ends "-500k" and is the correct size. A more conventional program would also be fine. The trouble is there are many editors, but I can't find the feature I am looking for. At the moment I have to use trial and error.

Any ideas?

(I prefer an open-source solution, I don't want to use Lightroom or similar that requires importing images first).

 

[drounding]

I doubt you'll find a utility that does that based on file size alone as it would need to be a recursive process. The new reduced file size wouldn't be known until the image had already been compressed (Just what you're saying by trial and error), The resultant file size would be a combination of many factors in the image including of course the output format.

As you say there are many programs out there that will do almost anything else. I personally use FastStone Photo Resizer for batch conversions for the web but there are so many others.

Why is a specific size so important to you?

 

[Kodiak Qc]

•
From within any decent Raw converter, one may batch resize to any format and
size for print or web.

 

[sirch]

JPEG is a compressed format and as Duncan says the final size in bytes won't be known until the compression has been applied and the amount of compression will depend on the contents of the image file.

That said, I use Prish Resizer which kind of does what you want, right-click selected images in Windows Explorer choose "Resize" and then choose an output size in pixels. Assuming your input files are all the same size a bit of trial and error will allow you to determine a pixel size that gives something like the file size you want.

 

[drounding]

•
From within any decent Raw converter, one may batch resize to any format and
size for print or web.

True Kodiak - I never noticed before that before. There is a selection in LR to limit the max physical file size instead of adjusting the image quality.

I suspect that with a max file size images with a large number of contrasting pixels for example might need to be compressed much more than ones with lower contrast and fewer colours say (depending on the compression percentage and algorithm). You may end up with some images looking worse than others.

 

[Kodiak Qc]

…I never noticed that before…

•
I do not use LR but the RAW converter I use is giving me the consequent final
file size and updating it as I change the reduction parameters.

 

[Andy Taylor]

Have a look at Irfanview. It is free for personal use (not open source) and will allow you to specify an output file size.
When I was a windows user, this was my main tool for viewing and resizing files.

 

[StewartR]

Why is a specific size so important to you?

This is an important question. Some images will stand up to compression quite well; others - typically those with fine detail - could be quite badly degraded. Choosing a specific file size, rather than a compression level, strikes me as a bizarre requirement. What is driving it?

 

[boyfalldown]

I know you don't want to use LR but there is an option in the export dialog that allows you to control an image file's size. Why you'd want to is another matter

 

[Neil Pho]

Have a look at Irfanview. It is free for personal use (not open source) and will allow you to specify an output file size.
When I was a windows user, this was my main tool for viewing and resizing files.

Thanks. Irfanview with a plugin does what I want. It's lightweight enough and, though it lacks windows integration, it's painless.

 

[Neil Pho]

•
I do not use LR but the RAW converter I use is giving me the consequent final
file size and updating it as I change the reduction parameters.

Why don't you just tell us what you use?

I know the option exists in Lightroom, but I haven't yet found it in Capture One

 

[Neil Pho]

I don't want to be resizing images by filesize. And indeed the image pixel size will vary greatly depending on the contrast and noise in the image.

But, unfortunately, some websites limit images by KB.

 

[Kodiak Qc]

I know the option exists in Lightroom, but I haven't yet found it in Capture One

•
The Capture One website is offering plenty of videos that explains in great details
all the features!

 

[Kodiak Qc]

I don't want to be resizing images by filesize.

•
I think you've got something very wrong here!
From within any RAW converter, the size of your files is irrelevant! what matters
is only the size you want to publish your final renditions to.

And indeed the image pixel size will vary greatly depending on the contrast and noise in the image.

•
Please, tell me where you got such disastrous information!
A final rendition pixel size is determined by the values you fill in before publishing
and have nothing to do with anything else. Now, this being said, the compression
quality will make a big difference in memory size but will not affect the pixel count!