Reducing Photo Weight from 999KB to 99KB on MAC OS X Without Cropping: How To?

Question

When it comes to changing the height and width of the photo, I do not have a major problem with it, but I do not know what to do when I have adjusted the height and width to the requirements, but the weight of the photo is too large, e.g. how to reduce the photo from 999 KB to 99 KB or less ?...

marcode · Accepted Answer

Save in .jpg format and set zip compression which reduces weight and quality.

Anonymous · Accepted Answer

It depends on how much you want to slim down the photo. JPEG is a lossy compression, so the higher the compression rate, the lighter the photo, but forget about enlarging it (details and resolution will deteriorate). Oh - as for max. compression, the photo is still too heavy, you can compress the resulting file again ... Also at the beginning set the slider to 3/4 and see / evaluate the result and increase if necessary. Unfortunately, it should be done experimentally. Of course, do not lose / overwrite the original photo!

marcode · Accepted Answer

save as jpg and options in a new window

DriverMSG · Accepted Answer

IrfanView

deus.ex.machina · Accepted Answer

png is a lossless format, set it to 10 - the highest compression rate won't even change a single pixel

Lossless compression has one disadvantage - the file size (except in special cases) is usually much larger than the file size after applying lossy compression.

You can try to reduce the entropies of the source image - try denoise / median filter.

mirini · Answer

Many thanks Marcode. I have a JPG format, but if you can, please let me know how to set the compression with the slider?

mirini · Answer

Thank you Mariopi for valuable information, but I did not understand the second half of the sentence. I do not know where in the program the preview is the slider you describe that should be set to 3/4 ? I already have JPG photos in the original, so I have only changed the dimensions of the height and width in them so far. Now I have to reduce the weight from 999 KB to less. Thank you for your help.

marcode · Answer

So maybe it's time to install some normal photo application that allows you to choose the jpg format and compression level when saving the photo?

Anonymous · Answer

From such open source applications, I can recommend, among others GIMP. I use Linux on MAC-OS as well.

mirini · Answer

Thank you Mariopi and Marcode for valuable information. I already own a GIMP, but can't find an option to reduce the 999KB photo to less. Could I still ask for help? I don't even know what exactly is the name of what I want to find in google information, because reducing the burden is definitely a wrong concept.

Frog_Qmak · Answer

Exactly - irfan view. Save as, advanced options and you can adjust the parameters there

deus.ex.machina · Answer

Just remember to use an encoder that uses floating point numbers when compressing jpg, it is worth checking Huffman table optimizations - both settings allow you to improve the quality and reduce the resulting file size at the same time.
Compression settings in the case of jpg usually range from 1 to 100 (% by default), usually 100% means practically lossless compression, and 1 (sometimes) the lowest possible quality - from my observations it results from the 90% setting, which gives a high-quality and relatively small image / average file size, in my opinion it is not worth going below 75 - artifacts typical for jpg compression (DCT) are starting to appear.

mirini · Answer

I would like to thank all forum members for their help. Unfortunately, when it comes to the IrfanView program, I can't have it because I have MAC OS X, and from what I can see only Windows users may be interested in it.

I already have a GIMP program, I opened a photo in it, and read that instead of an option save as I should use export as . Then I saw various options which I took a screenshot, and if someone can help me, what should I select?

DriverMSG · Answer

At the very top, you have the quality slider. Besides, a little more initiative. Write down a few of the different options and see what the effect will be. PS:

deus.ex.machina · Answer

Most of the default options are ok with the exception of the DCT method - make it floating point. Slider at 90, uncheck the original image quality setting, you can uncheck EXIF and XMP - the metadata associated with the image will not be saved. You can choose sub-sampling 4: 4: 4 this is the highest quality by 4: 2: 2 is the average quality (a good compromise between the file size and its quality) to 4: 2: 0 - the smallest file, acceptable quality - it all depends on the purpose of the image - most consumer sources are 4: 2: 0, which is OK.

mirini · Answer

Thank you for all your help. Many thanks to Deus.ex.machina for the detailed information. I already understood the subject, but it turned out that I must have the PNG image format. and JPG is not accepted. When I chose the PNG option in the same GIMP program, I saw different settings. I've lowered the ratio from 10 to 1 and still don't have the 1MP that the image should have. The photo is 13.5 MB. I took a screenshot of the settings screen and would appreciate your help.

DriverMSG · Answer

And what resolution do you need to keep? What are you writing about now?

marcode · Answer

I don't know why my post was deleted so I will write it again, choose JPG instead of PNG and set the compression level with the slider.

deus.ex.machina · Answer

By the way, you can try to change the file extension from JPG to PNG (compress jpg but change the extension to png - somehow, despite the passage of several decades, many x86 programs only use the extension).

mirini · Answer

I have already dealt with the problem. First, in the preview program, I reduced the photo resolution (height and width). Then I opened it in gimp, set option 10 and sent it in png format. I did it many times until I finally cut the image in the preview so that the gimp program would format the image to 1 MB. I give different sizes of photos as these are the requirements depending on the company. I wanted to thank you very much for your help.

Reducing Photo Weight from 999KB to 99KB on MAC OS X Without Cropping: How To?

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