Reducing Images

[Lee]

I can't believe that I'm asking a question that, 30 minutes ago, I thought was elementary and a no brainer.

Here it is: When I went to reduce an image to use as an avitar I pulled up the image in PS, went to Image Size>Pixel Dimensions and entered 75X75 pixels (the max allowed by this site for avitars). When I checked the size of the image after that reduction it was still too big at 28k. I then reducted the dpi to 72. Still no luck. I reducted the image again to 60X60 and the dpi to 60, then 50, then 40 etc. It was not until I got to 40X40 and a dpi of 30 did the size go below 10K but by then the image quality was destroyed. Obviously I am doing something wrong. [confused]

Advise please. As always, thanks in advance.

Lee

 

[AppleCider]

Hi, Lee

First, for anything you put online, you should always start with a 72 dpi image. Anything greater is wasted for screen viewing.

Second, did you save your image as a gif or jpg? (File > Save for Web). That will reduce the file size. Save as either depending on the nature of the image. If it's a gif, play around with the amount of colors which can dramatically reduce file size. If it's a jpg, reduce the quality until you can't stand it anymore, then gradually increase it until it looks good.

In general, a 75x75 pixel, non-animated, jpg or gif image shouldn't be over 10K.

 

[Erik]

Sorry , Julie, but this is not true.

All a monitor cares about is how many pixels an image has. Dpi settings have no influence at all. Dpi is only useful for print, and is based on the old printer unit of pica.
You can still find this in the Photoshop preferences. The original pica was divided into points (72,27 per inch) and PostScript simplified this to 72. Apple originally used this for their mac because it was meant to be used in the dtp world.

The size of the "dots" on your monitor are set by your operating system that drives your graphics card. Examples: 800 pixels wide on 600pixels high, or 1280x960, or 1200x1600.
And if your image measures 900 pixels wide and you can display 800, then it does not matter whether it is set to 5dpi, 72dpi or 900dpi: you will have to scroll.

What the 72 does influence is the size of the print you can make from the image. If you only use 72 of the available pixels for one inch, then you have more inches, so the image is larger, but if you use 200 the image will be smaller, but of a much better quality.

To recap: only the number of pixels is important for online and web work, forget about the dpi.

Lee: did you save as jpg, or gif? (save for web). And did you use the settings to give a better compression?

try under Help> jpg and gif. Use jpg for photographic-like images, and gif for simple colours like in a children's colouring book.

 

[Lee]

It was originally saved as a Jpeg. I know what a tiff image is but until you explained it I didn't know what a gif image was or what it was used for. Thanks for the explanation.

As to using settings for better compression, Erik, I didn't as I don't even know what those are.

I will go back and try using the gif format and see what happens. I will look under help as you suggested but, for my education right now, where are the compression settings located?

Thanks again.

Lee

 

[Erik]

These are the most basic settings.

Short explanation (simplified):
To remember an image (i don't talk about vector files now), a puter divides it into a kind of mosaic, and of every buiding bloc it remembers the place and how much red, green and blue it has. This way it can reconstitute it afterwards. Every one of these building blocs is called a pixel. And all the size/place the info takes on your hard drive or memory is called the file size.
what jpg and gif do is make the file size smaller. They do this by remembering pixels that have the same information on colour, or by forcing pixels to the same information on colour. It's easier to remember that those tenthousand pixels have this particular setting for red, green and blue that to have to remember it for every pixel separately. That is how the size in byte (kilo, mega, giga byte) is reduced.

Here are your settings. The lower you set the jpg quality slider, the lower the quality (it forces pixels to the same values), but the stronger your compression and thus the smaller your file size.

Try in the case of the avatar thesmall arrow I indicated. You will find in the dropdown list an option to reduce to a file size you can set. Choose that, and fill in what you want, then click ok.

This image is a typical gif: clearly cut colours, no gradations, no skies, landscapes, skins etc...

have fun!

for this: go to the File menu and choose>Save for Web. At the right you see one of these dialogs. Click where indicated to get the other one.

 

[Lee]

Erik, thank you for the explanation. It helps me understand what I'm doing besides just following directions well.

FYI - I did a "save for web" and, voila, the image was instantly reduced to 6.8k. All that stuff I was going through was wasted as all I had to do was understand what the image was going to be used for - a web picture - and use that option. Again, thanks.

Julie, thanks you for your explanation, too. I love all the knowledge I can get as it just adds to the learning process.

Later, guys.

L