[1ponders]
17-02-2006, 06:10 PM
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
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