An overview of image compression tools

To speed up the site, some recommend analyzing each page: optimizing HTTP requests and any redirects, compressing scripts and styles, etc. All this is without a doubt necessary, but first of all it is important to consider the basics. In particular, are you sure that any graphics that you use on the sites you create are fully optimized for the Internet?

Almost all web developers know that it is necessary to choose the appropriate format for each image, as well as minimize its size (in pixels and kilobytes). Some even optimize JPEG settings as much as possible, balancing between size and quality. However, the harsh reality is that, no matter how carefully you design your images, the regular image editors you use will not be able to save the finished files as efficiently as possible. And when compressing images, their quality can deteriorate significantly.

It is difficult to say for sure how much quality is lost during image compression, as this largely depends on the graphics source. Some JPGs can be reduced by only 50-100 bytes. Usually, normal Internet graphics need to be compressed by 10-40%, without loss of image quality (this can also be done with a decrease in the number of colors or with the conversion of JPEG files to other formats). But ideally, to compress images, use special programs or web services, which will be discussed in this review.

Testing

So which programs are better? To give the answer, we will consider 18 main programs competing among themselves. These are mainly image compression tools for Windows, as they are the most common. But we also included lossy compression options, Mackintosh programs, and web services, so there is hope that everyone will find something useful for themselves.

We tried using each program to compress the same sets of GIF, PNG and JPG images, each of which was actually a sample of the web graphics we found on a number of real sites. A program check was also performed on other items. Are they user friendly? How fast was the compression process? Reliability? Can a program, for example, increase the size of an image?

The results were very interesting, we invite you to familiarize yourself with them.

Programs

1. AdvanceCOMP 1.15

Platform: Windows An

obsolete tool using the command line and with minimal support. AdvanceCOMP is unlikely to be suitable for the average PC user who is used to graphical interfaces. For those who are used to working with the command line, there is nothing complicated in it. So, just one line:

'for %a in ("C:\PNG File\Folder\*.png") do advpng -z -4 "%a"'

allows you to apply a lossless compression algorithm for each file in a folder, replacing the original with a compressed version.

Nevertheless, the results obtained were far from ideal, and our test PNG image shrank by only 14.2% (only one tool from the services included in the review turned out to be even worse).



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2. Caesium 1.4.1

Platform: Windows

Caesium is a simple open source tool designed to compress PNG, JPG and BMP. This is a fairly convenient program to use. Click the Add button, select the images, select the folder where the processed images will be downloaded - Output, click the Compress button, and after a few seconds you will get the result.

BMP compression is not of interest to us, as it is rarely used when creating sites, and JPG compression technology also did not find anything special for us. The program does not have the ability to compress without loss of quality, it simply transcodes the file in the selected quality setting.

Caesium does provide support for PNG compression without quality loss, although it does have some limitations. It can only output 24-bit images, otherwise the image size is likely to increase. The results of the program clearly illustrate the problem, since most of our test images of PNG web graphics with a color depth of 48 bits actually increase in size. Even with careful adjustment, the overall size of our image was reduced by only 1.2%.



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3. FILEminimizer Pictures 3.0

Platform: Windows

FILEminimizer Pictures takes a more radical approach to image compression than most of its competitors. By default, when you try to compress your photos, it can change the format and size of the image, transcode JPEG files with lower quality and cut out metadata. Most of these options can be set in the program settings.

In use, the program adheres to the generally accepted principle. After you indicate the source file to it, select the folder for the result, you may have configured one or two options, just one click of the mouse to start the optimization. All of this is pretty fast, so you don’t have to wait too long.

How well does compression work? Everything varies depending on the format, at least in our tests. PNG compression - nothing special - 26.8% (some tools do better without loss of quality), GIF compression was above average - 16.5%, but our JPG internet graphics decreased by 39.3%, - the largest compression in the study group. But in all tests, the loss of quality was visually noticeable.



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4. FileOptimizer 2.10.135

Platform: Windows

Features FileOptimizer are quite large. It can not only compress JPG, GIF and PNG images, but can also work with executable files, archives, Microsoft Office documents, PDF files - the list can be continued for a long time.

Surprisingly, while using it is absolutely not difficult. In fact, the program has one of the simplest interfaces: drag and drop images into FileOptimizer, right-click, select Optimize / and enjoy the result. However, this simplicity also has a downside - the source files are replaced by the program. Originals are sent to the basket, so they will have to be restored (if you need them, of course).

But of course, compression is of utmost importance, and here FileOptimizer provides good results. For example, the program reduced our test graphics PNG by 42.2% - this is the best compression without loss of quality in this group. Compression of JPEG and GIF was 17.7% and 15.9% higher than the standard, respectively, but in this program there are still many useful options that you can use with FileOptimizer to compress other files on your site.



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5. ImageOptim 1.4.0

Platform: Mac

ImageOptim is a Mac tool that optimizes GIF, JPEG and PNG images and also acts as an interface for many other applications: PNGOUT, AdvPNG, Pngcrush, advanced OptiPNG, JpegOptim, jpegrescan, jpegtran and Gifsicle.

The program performs compression almost without loss: rather, comments, color profiles, etc. are deleted, without re-encoding or reducing the number of colors. ImageOptim interface is also very convenient. Drag one file, group or folder with the necessary files, and the program immediately begins to compress each image and display the results. It is not the fastest tool, but even if you send a thousand high-resolution JPEG files for processing, this is unlikely to be a problem for her.

The end results were impressive, but not spectacular. Our web graphics GIF decreased in size by 16.2%, PNG - by 17.8%, JPG files - by 18.3%. You can do better with separate tools. But if you need a simple Mac tool that can handle GIF, JPEG and PNG files, then ImageOptim is a smart choice.



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6. JPEGmini

Platform: Mac

JPEGmini is an interesting Mac application with a non-standard approach to reducing JPEG format.

Firstly, it uses an intelligent algorithm to find out how much the image can be compressed without a visible effect (that is, not a simple recoding with some kind of fixed quality setting). The program uses its own JPEG encoder to try to get the most compact files possible. Processing is done in the background. Just drag and drop your photos into the program (maximum 20 per day in the free version) and it will replace the originals with compressed versions.

But the range of results was huge. Our JPG picture decreased by only 8.2%, but when we sent 25 large digital photos for processing, they decreased by 71.3% with a slight visible loss of quality. With simple web graphics, JPEGmini does nothing too surprising. It is best used for processing large-sized images.



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7.jStrip 3.3

Platform: Windows

jStrip is a JPEG compression-free compression tool that removes irrelevant information: thumbnails, comments, color profiles, extra bytes at the beginning or end of the file, and various other bits and pieces. But file compression will be small, because the program does not use re-encoding. This was especially noticeable when we placed high-resolution JPG photos on the JStrip, which the program was able to reduce by about 1%.

If the files you want to compress are already small in themselves, the compression is likely to be much more significant. When we passed our selection of JPEG web graphics through jStrip, images were reduced by an average of 16.1%. It is worth noting that the program is not stable. By default, it replaces the images you specified with compressed versions, so it’s better to use copies for processing. In general, jStrip is a quick and easy way to slightly reduce the size of JPEG images.



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8. OptiPNG 0.7.3

Platform: Windows

OptiPNG is a popular PNG compression tool without loss of quality using the command line, which is regularly used in other programs (for example, PNGGauntlet) for image processing and optimization.

The program is much better documented than many similar packages, so even if you did not work with the command line, then it will be easy to figure it out. Installation files are downloaded along with the PDF file, where various switches and options are explained, which is very convenient (although you still need to practice image optimization to fully understand how it works). If you want to combine several tools with the command line to get the best results, OptiPNG should be included.

The results, even with default compression settings, turned out to be quite acceptable: our test web graphics PNG decreased in size by an average of 32.2%.



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9. PNGGauntlet 3.1.2.0

Platform: Windows

PNGGauntlet is a pretty interesting tool, essentially a wrapper for three other open source programs (PNGOUT, OptiPNG, DeflOpt) designed to compress images.

In the process, she acts in the same way as competitors. Drag the source images, select the output folder, click the “Optimize! / Optimize” button! and wait.
It is possible that you have to wait, and wait, and wait ... Presumably, such a long wait is due to the fact that it combines the work of three processing tools. PNGGauntlet can be very slow, in our case it took 50 minutes 44 seconds to compress 25 high resolution photos in PNG format.

However, the results are impressive. When processing our test web graphics PNG, the program reduced our 50 images by an average of 41.3% and even photos decreased by 7.75% without any visible loss of quality. Sometimes this is enough to justify performance issues. Therefore, if you need a quality PNG compression tool, then PNGGauntlet really needs to be included in your list.



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10. PNGOptimizer 2.2

Platform: Windows

With a tiny size of 146 kb, PNGOptimizer is the lightest of the programs presented in this review, so it is not surprising that its interface is as simple as possible and it specializes only in PNG files.

Using PNGOptimizer 2.2 you get the ability to control a surprisingly large number of processing parameters. PNGOptimizer can remove interlaced frames, save, delete or replace the background color, as well as delete text or physical image dimensions in pixels. The program can even import GIF, BMP and TGA files, saving them in PNG according to the selected options.

But the program was unable to outperform competitors in image compression, this can be seen from the test results. PNGOptimizer reduced PNG high-resolution photos by an average of just 3.6%. She handled small graphic images much better, with an average compression of 39.8%. If you need a small and simple PNG compression tool, then PNGOptimizer is what you need.



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11. PNGOUTWin 1.5.0

Platform: Windows

PNGOUT is one of the best image compression tools. Unfortunately, it is rather inconvenient to use, because it is created on the basis of the command line without support for batch processing. But if this is a problem for you, you can always choose its commercial interface: PNGOUTWin .

The program is easy to configure. You can use PNGOUTWin to overwrite your original images or save the weekend in a new folder. It is also possible to save file attributes of time, adjust the compression level, the ability to store some (or all) pieces of PNG, etc. is implemented.

It is also easy to use. Drag the image into the program window, and it will immediately begin the compression process, using several threads to work simultaneously with several images. The results are also excellent, our PNG web graphics decreased in size by 40.5% (not bad for compression without loss of quality).

Unfortunately, at present, only the PNGOUT interface is free for it, just like PNGGauntlet, which is also very easy to use (in fact, you can achieve even higher levels of compression if you combine it with other tools). Although PNGOUTWin is a powerful program, it is probably not worth the $ 14.95 (personal license) / $ 29.95 (corporate license) they ask for it.



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12. PUNYpng

Platform: web

Much more universal than its name suggests is PUNYpng, a web service that can actually apply lossless compression to GIF, JPG and PNG images. Registration and account creation are free, but there are restrictions for free accounts: you can upload only 15 images in batch mode, each no more than 150 kb.

In general, the service is quite convenient. Click the Upload Images button on the site, and then wait while the photos are uploaded and compressed. A progress report appears, and everything can be downloaded as a ZIP archive.

For testing, we used a free account. PUNYpng showed good results and compressed various test suites of files by 16-32%. For $ 2 per month, you can upgrade your account to PRO, with which you can get an additional compression option with less loss of quality and upload more files.



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13. RIOT 0.4.6

Platform: Windows

RIOT is free, but it is one of the few programs that tries to install additional software during the setup process. Be sure to uncheck the corresponding box during installation if you are not interested in such additional software.

Everything else is very simple. A clear and intuitive interface allows you to easily compress individual GIF, PNG or JPG images and compare the results, while the batch interface processes several files at a very high speed.

Unfortunately, there is no compression without loss of quality. RIOT, rather, reduces the number of colors in the image and transcodes in JPEG format with a low quality value. Despite this, the program managed to make some of our test images significantly larger. Therefore, we recommend that you carefully check the output settings of the RIOT before using it for processing.

The program nevertheless coped well with the task, in particular, it managed to reduce our GIFs by an average of 42.8%. But before, a detailed configuration was needed - the “default” indicators were much worse.



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14. ScriptJPG

Platform: Windows

ScriptJPG is one of the most primitive packages, in essence it is just a script for Windows that acts as an interface for several command-line tools. Drag and drop your JPG files into the script, select the compression options (either without losing quality, or with a special JPEG quality setting), and ScriptJPG will reduce your images. So, at least, it was stated in the description. For some reason, the program did not work with our JPG web graphics as promised, and the start menu did not even appear.

We were able to test the package in our JPEG photo, and got good results. Its compression option without loss of quality has reduced the size of our image by almost 10%. If you are a graphics specialist, then ScriptJPG may be of interest to you. You will be able to diagnose problems as they arise and, possibly, change the script, adjust the compression settings to suit your needs. If you prefer more understandable and simple tools, we recommend using one of the analogues with a graphical interface. There are many more powerful alternatives and, of course, they are much easier to use.



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15. ScriptPNG

Platform: Windows

As you may have guessed from the name, ScriptPNG is the closest relative of ScriptJPG. It is a Windows batch file that uses four utilities to compress PNG files to the desired size. As with ScriptJPG, there are very limited customization options here. Drag the image to a file and nine possible compression options open on the command line. Choose the one you need and the program will immediately begin to cut each file in turn (and replace the original images with the output, so it’s better to work with copies).

Another problem we had was that pngout.exe crashed after installation. This did not appear on the execution of the script, but we had to manually close the error dialog box each time as soon as it appeared. Despite this, the compression results were quite impressive. Our PNG web graphics lost up to 40.1% of the volume without apparent degradation in image quality.



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16. Smush. It

Platform: web

Most web services for image compression have great limitations, but Smush. It on Yahoo is a rare exception. The only limitation is the file size (not more than 1 Mb), but you can upload as many images as you need to the system. There is no registration, no account creation, no daily quotas. Images are compressed using various tools, and the results can be obtained as a ZIP file.

This approach has only one problem - you do not have access to the compression tools themselves. You cannot configure or change them. You see the results you get and you can’t do anything to change them. Some problem was found with the jpg files since Smush. It managed to reduce our test images by only 1%. PNG compression was more efficient - 35.3%, although our GIFs lost an impressive 23.9% of the volume (the best compression without loss of quality in all tests).



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17. TinyPNG

Platform: web

Like Smush. It, TinyPNG is a free web service that can optimize images for you. Just drag and drop your files onto the web page, it will compress them and provide download links. The system has some drawbacks: a file size limit of up to 2 MB, the ability to download only 20 files at a time, and the lack of the ability to batch download.

TinyPNG also clearly shows the approach to compression due to quality, unlike most other tools, and it revises the palette to reduce (sometimes significantly) the number of colors used. Unsurprisingly, this justifies itself in terms of raw drawings by compressing our PNG web graphics by 48% - the best result in this test. In most cases, it was very difficult to detect any differences between the original images and the compressed versions.

By the way, the best compression rate without loss of quality among locally installed programs is 40%. Therefore, if your main priority is image quality, or you just don’t want to constantly compare the graphics, trying to see if there is a difference, then TinyPNG may be of interest to you.



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18. Trout's GIF Optimizer 2.3

Platform: Windows

Trout's GIF Optimizer is a compression tool that does not require installation. His options, of course, are a bit limited. As you guessed from the name, the program only compresses GIF files, so it does not have any global configuration parameters that are of particular interest (although you can manually optimize the palette of individual images in various ways).

However, with Trout's GIF Optimizer, it’s very easy to work with. Just import the selected photos, the size reduction for each image is displayed immediately (it is very fast), you can save them with just a few clicks of the mouse. But, unfortunately, the compression results are not particularly impressive: our web graphics GIF decreased by an average of only 16.7%.



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Summary table for all tested services

Протестировано	Платформа	Сжатие	Уменьшение PNG (в%)	Уменьшение JPG (в%)	Уменьшение GIF (в%)
AdvanceComp 1.15	Windows	Без потери качества	-14.20%
Caesium 1.4.1	Windows	С потерей / Без потери качества	+18.7%
FILEminimizer 3.0	Windows	С потерей / Без потери качества	-26.8%	-39.3%	-16.5%
FileOptimizer 2.10.135	Windows	Без потери качества	-42.2%	-17.7%	-15.9%
ImageOptim 1.4.0	Mac	Без потери качества	-17.8%	-18.3%	-16.2%
JPEGmini Lite 1.4.1	Mac	Без потери качества		-8.2%
jStrip 3.3	Windows	Без потери качества		-16.1%
OptiPNG 0.7.3	Windows	Без потери качества	-32.3%
PNGGauntlet 3.1.2.0	Windows	Без потери качества	-41.3%
PNGOptimizer 2.2	Windows	С потерей / Без потери качества	-39.8%
PNGOutWin 1.5.0	Windows	Без потери качества	-40.5%
PUNYpng	Web	Без потери качества	-32.1%	-27.5%	-16.1%
RIOT 0.4.6	Windows	С потерей качества	-21.7%	-39%	-42.8%
ScriptJPG	Windows	С потерей / Без потери качества		-10%
ScriptPNG	Windows	Без потери качества	-40.1%
Smush. It	Web	Без потери качества	-35.3%	-1%	-23.9%
TinyPNG	Web	С потерей качества	-48%
Trout’s GIF Optimizer 2.3	Windows	С потерей / Без потери качества			-16.7%

Выводы

After hours of testing and the general decomposition of the participating programs into stages, we can conclude that image compression is really an effective optimization tool and gives a pretty good result. All of our test PNG files could be reduced by 30-40%, and even JPEG files could be compressed by 16-18%. In all cases, compression was used without loss of quality, so the image quality did not decrease, the images look exactly the same, they only load faster.

The exact results that you get, of course, may vary. But if you haven’t tried to compress images before, then it’s definitely worth taking the best of our programs and trying to see how they can be useful for your sites.

In general, FileOptimizer turned out to be better than its Windows counterparts in compression without quality loss, demonstrating excellent compression (up to 42.2%) of our test files. It also compresses files with the JPG and GIF extension well, and it also has other useful options (for example, PDF compression).

But if for some reason this program does not suit you, then PNGGauntlet and ScriptPNG also provide good PNG compression, and ImageOptim is useful for Mac, since it provides a good level of JPEG and GIF compression.

Although we found that web services were less convenient to use during testing, we would not completely exclude them. PUNYpng was the best at compressing JPG without loss of quality, and Smush. It defeated all competitors in GIF compression, both of which can be of great help in reducing the volume of your web graphics.

Source

P.S. Unfortunately, this review does not mention another very effective tool (thanks dersmoll and alekskorovin noticed this while preparing weekly digest), which has already been referred to Habré.

UPD Thank you very much to users who shared their own options:

@yourway for Color quantizer (really interesting, in my opinion).

azproduction for the much-needed option for OSX & Linux imgo

LuckyReveal for kraken.io

Pros: High compression, speed, public API (free).
Cons: A limited number of requests per day. (50 per day, each no more than 500kb).

It can be installed as a plugin for Chrome: goo.gl/aDSQ6, Firefox: goo.gl/mlxd0.