One of the issues that many newbies (and some not so newbies) come up against is how to reduce their image quality (Kbs) for upload yet still retain acceptable dimensions (size) to achieve the full effect of the image. Quite often we see images that are only relatively small dimension wise but if you check their Kb they can be way over the guidelines limit. Or alternatively they are fine in size and have very low Kb which doesn't show the image in its best light.
Uploading images to the web is often a fine balance between size and quality. Fortunately PhotoShop has a fantastic tool to help reach this balance and unlike many Photoshop tools you don't need a degree to use it. When I was first introduced to it I found it quite intuitive. So to help those who often struggle with this problem of size verses quality I've prepared this little visual demonstration.
When working in TIFF format (which is very common for astrophotography) my files can be as large as 36mb. To reduce them for upload I use PS "Save for web" command. Now the following demo uses an image that is only about 13 mb and is a Bitmap, but the prinicple is the same.
In Image 1 you see at the bottom in the status bar the original image is 13.1 mb, way too big. To reduce it the first step is to go File>Save for Web (Image 2). The save for web page opens. Now you may find that your page view differs from Image 3. Check the tabs at the top of the page and select "2 Up". This will show a "Original" and an "Optimized" view. Use the magnifying glass to zoom out (if you don't know how to do this Click the magnifying glass icon at the side and then hold down the alt key while clicking on the optimized image). Zoom out til you feel comfortable with the image size. You haven't changed anything about the image yet, just the view.
Now at the right of the page you will see the optimizing controls. Select Jpeg and medium quality (or set quality at 50%). Already my image has dropped to only 180 kb in size. and if I look closely by zooming in and out, the quality, while is isn't as good, hasn't dropped too much.
Next is to select image size. You will see in Image 4 that my image is fairly large at 2416 pixels wide. Now my laptop screen will only show 1280 pixels wide, so anything wider is a waste of image, plus if I keep it to screen size I may be able to up the quality and still keep it under guidelines. But I am also conscious of the fact that many users can still only get dialup, so I don't want to disadvantage them. Again it is a balance. With this particular image I was able to keep the quality at 50% and drop the size to 1000 pixels (still a good size) and keep the image Kb to only 56kb (Image 5). Plenty comforable for dialup, still a good size and an acceptable quaility. Btw, you only need to put in one dimension, PS will automatically adjust the other. Once you input your image size you will need to click apply for it to take affect. Adjusting the image quality responds automatically. BBtw at the bottom of each of the image panes is the approximate time it takes for that image to load at 28.8 kb/sec is given. I often use this as a guide for loading times for dialup users. If its a smashing image I can be forgiven for long loading, soso images I try to keep down.
You may find that you have to "fiddle" with these options to get the desired effect, you may even have to save the original image as either a bitmap or jpeg and then try to optimize is to meet your requirement. I have found this a great way to optimize at it allows me to see in real time how the changed image looks as well as its size.
Finally in Image 6 you will see the save options. I usually simply save it a an image (jpeg) and don't worry about the other options. Once you click save the Optimize page disappears and takes you back to your original image in PS. When you close your image you will be asked whether you want to save changes. I just click no as I don't want to change my original.
Now you have a reduced copy of your original that will take less time to upload, meet the forum image guidelines and take less time to load for those who wish to see your images.
Hope this helps. If anything is unclear, or you know this process and think I've missed anything, let me know and I'll try to clarify the process or update this guide.
Cheers
Last edited by [1ponders]; 17-02-2006 at 07:00 PM.
Paul, the principles are all good, but Photoshop is a rather expensive piece of software, so most people wouldn't (or at least shouldn't) have it. But there are lots of completely free programs available to accomplish the simple task of resizing images cleanly. (There are also excellent free alternatives to the PS program itself for those who cannot afford it or think it is overpriced.)
I know that a lot of people use programs like Gimp etc Steve but this was done for those who have PS and want to start to learn how to use it or are just unaware of this ability
It's all good Paul. Sorry, just thought I'd butt in, given that (I assumed) PS costs more than many newbies would be willing to pay for a scope. But as I am replying, I'm looking up how much PS actually costs, and the "Elements" version sounds very reasonable, but the cost of "CS" is just nuts.
I think also that PS Elements now comes bundled with some of the new Digital Cameras so it's worth noting this advice for newbies and not so newbies.
I use this feature in CS all the time and find it very handy.
"nuts" doesn't do it justice There are also student and teacher versions available that have most of the functions. They can be reasonably priced. For Photoshop that is
Another option for thoses looking for PS is to keep an eye out for older versions like PS 6 and 7.
I find the free image resizer from microsoft is unbeatable if you're using XP. I use others including photoshop and paintshop, but my first choice is always the powertoy as it's integrated in to the explorer shell and you can resize a file in less time and clicks than it takes just to open the file in photoshop. Files are simply selected by clicking in explorer and right clicking to select resize. Multiple files can be resized by using standard ctrl, shift, click techniques during selection. http://download.microsoft.com/downlo...ertoySetup.exe (small only 520Kb Download)
True Phil, it's a great little application, and it's one I used to use regualrly when working with jpegs. But as I was pointing out, now many of my images are processed in Tiff (16 bit) at 36 mg and using the MS resize even at the smallest setting wont reduce it in size enough. The bmp Orion I used only reduced to 3.1 meg even at the 640x480 setting, and I still had to convert it to a jpeg and it still came in at 90 kb.
The biggest plus I find with this technique is I can do all my processing in PS and when I'm finished a couple of clicks and the resize is done into the folder I want it to go to and ready to upload. Otherwise I have to convert my Tiff from 16 bit to 8 bit, then save as a jpeg, then get to the jpeg in windows explorer, resize it then move it to my upload folder. If I'm working aready in Jpeg it's not such an issue, but in larger files if I'm already in PS I find this a much quicker and involve less steps.
Certainly if the main object if for someone to resize an existing jpeg it is a great little application. But for working with 16bit large files (or even 8 bit) I find the funtionality afforded by Save for Web, especially the ability to match quality with size of file, a great image management tool for uploading high quality astroimages
I'm with you Paul, Sure their are some great free applications out there but nothing comes close to Photoshop CS...sure it's an expensive program if purchased but it seems anyone interested in Astrophotography has it anyway.
Thanks for the info Paul. Apart from the fact that I don't normally have much patience. Your instructions were pretty easy to follow and actually worked. (no disrespect to you, moreso my lack of ability to follow instructions).
Is much appreciated. As others have mentioned there are probably many other programs out there that will give the same result, in this instance I have a very early edition of photoshop and it works for me.
Thanks Paul. I tried this tonight (and posted a pic of the Parkes Radio Telescope in General Photos) and it works well. I haven't used it before, I usually resize the image and save as, etc but this takes the guess work out of estimating the filesize at the end, and I think helps eliminate the risk of choosing "save" instead of "save as"... ... hate that!
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There are also student and teacher versions available that have most of the functions. They can be reasonably priced. For Photoshop that is 
Thanks for the info Paul. Apart from the fact that I don't normally have much patience. Your instructions were pretty easy to follow and actually worked. (no disrespect to you, moreso my lack of ability to follow instructions).
... hate that!
