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I have a 3.05 MB image that I must reduce to 1.8 MB without changing the pixel size of 1920 x 1920. Can this be done?

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What's the format of the original image? – haimg Jun 8 '12 at 22:29
Like this: – iglvzx Jun 8 '12 at 22:30

Consider using ImageMagick (Apache 2.0 license, available for Windows) for mucking around with compression and quality, particularly if you have to do this in an automated fashion or over several files. You should be able to dial down quality with the convert tool:

convert -quality 75% input.jpg output.jpg

See ImageMagick v6: Common Formats: Writing JPEG Control Options for more info. Also keep an eye on the superuser and Unix & Linux topics for ImageMagick if you need further help.

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This is what I'm gonna use from now on, true Unix philosophy. I just needed to install ImageMagick via brew. It just works. – Reza Feb 2 at 10:18

You could upload it somewhere like

Basically does the same thing others suggested, except it allows you to do it online for free without installing extra software.

You can there change the quality (which equates to the end file size)

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morTie's solution is really a good one. To modify it very slightly, you could also use GIMP -- which is free, and available on Windows (

Start GIMP, open the file. On the image window, select File > Save a copy. Type in an appropriate filename - be careful not to overwrite the original. On the 'save as JPG' window, which looks like this:

Save as jpg window

pull down the 'quality' slider. You may have to experiment a little with different settings to find the appropriate value, but to give you an idea, I tried this with a screenshot from a game just now and I could turn down the quality to 66%, reducing the overall filesize from 180k to 80k, without any obvious loss of quality. However, this will vary a great deal with different images, so some trial and error might be involved.

By the way, if (and only if) the image is not a photograph but something that contains lots of block colours, then you might find that PNG produces a smaller file, so it's worth trying to save in PNG as well, to see what filesize/quality you get out of that. Compression level 9 is both the default and the maximum value. It did a terrible job with the game screenshot I used to test it, but then it was more like a photograph than a piece of line art.

saving in PNG

Regarding PNG, you might also try PNGNQi, which is a command-line programme, but if you download the Windows binary, unzip it, and then drag and drop your PNG image onto the BAT file named 'Process - Palette reduce 64 Median', it will (if it can read your PNG properly) generate a much smaller PNG file from the source.

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Load it into Photoshop then click save as and choose .jpg, reduce the quality and save it.

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-1, simply because Photoshop costs a couple of hundred dollars. Just to reduce the size of an image? Could you expand your answer to include some more practical ways, maybe with screenshots, et cetera? – slhck Jun 8 '12 at 22:34

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