Optimizing images that look good but are low file size, help

[BlackReef]

Hello,

I am dealing with images that are 900x400, and they are on this site:

http://www.gem-tech.com

I've used the 'image optimizer' in Paint Shop Pro, and I have gotten most of them down to under 150kb / per image but the image quality is really suffering on some of them.

I notice on other sites though - that images that are roughly the same size are only about 90kb or so, and the image quality is great.

What is the key to keeping image quality but keeping the image quality down?

Thanks!

[qwertyuiop]

Well a lot of it depends on the image format, the main 3 being .jpg, .png, and .gif.

JPGs are typically used for photos; images with lots and lots of colors and complex color boundaries etc... They are lossy, meaning when you save, you will lose some quality and get artifacts (nasty looking pixely areas), but have pretty decent file sizes (though that depends on how much quality you're willing to sacrifice)

PNGs are usually used for computer graphics, such as gradients, icons, translucent/transparent images... They have really good file sizes for what I listed, for images, not so much. They are non-lossy, so you will not lose quality and get those artifacts.

GIFs are useful (and small) for simple images that don't have many colors, up to 256 I believe. PNGs can do everything GIFs can (except animation) and more (alpha transparency)

Your jpg images aren't that large (150kb), especially now in 2010, where lots of ppl have high speed internet, although compressing and optimizing images is always a good idea. So the "key" to keeping file size down is to use the proper image format and compress and sacrifice as little quality as you are willing.

The images that were around 90kb likely had lots of one color (sky etc...), whereas yours have lots of complex patterns (tree branches etc..) This image is only 70kb, which makes sense, as most of the image is a green sky and some black cave.

I think the compression gives your images a nice nitty gritty look anyway.

Hope that answered your question

[BlackReef]

Originally Posted by qwertyuiop

Well a lot of it depends on the image format, the main 3 being .jpg, .png, and .gif.

JPGs are typically used for photos; images with lots and lots of colors and complex color boundaries etc... They are lossy, meaning when you save, you will lose some quality and get artifacts (nasty looking pixely areas), but have pretty decent file sizes (though that depends on how much quality you're willing to sacrifice)

PNGs are usually used for computer graphics, such as gradients, icons, translucent/transparent images... They have really good file sizes for what I listed, for images, not so much. They are non-lossy, so you will not lose quality and get those artifacts.

GIFs are useful (and small) for simple images that don't have many colors, up to 256 I believe. PNGs can do everything GIFs can (except animation) and more (alpha transparency)

Your jpg images aren't that large (150kb), especially now in 2010, where lots of ppl have high speed internet, although compressing and optimizing images is always a good idea. So the "key" to keeping file size down is to use the proper image format and compress and sacrifice as little quality as you are willing.

The images that were around 90kb likely had lots of one color (sky etc...), whereas yours have lots of complex patterns (tree branches etc..) This image is only 70kb, which makes sense, as most of the image is a green sky and some black cave.

I think the compression gives your images a nice nitty gritty look anyway.

Hope that answered your question

wow, thank you very much for your response, very good information here.

So, what I think I am going to do is just try to optimize all the larger images (900x400) to 150kb or less, and I think we should be fine. I have a few images over 300kb, will play with them a bit.

Thank you again, you have been very helpful