Reducing image file size

I see many PR members post photos in the forums at 800x600 pixels, with file size under 293.0KB. Yet the shots look very good, detail-rich and with no hint of JPG compression or pixelating. I, however, struggle to keep 600x400 pixel shots under 300KB!

What is your preferred method for reducing file size – and why. Here are some I can think up of, I often apply all of them:

• JPG compressing.
• Chroma subsampling.
• Stripping EXIF data.
• Deleting thumbnail.
• Resizing further.

Also are there any "tricks" for obtaining best possible image quality?

I use Lightroom.
I have a custom Export setting to save the file in the _UploadMe folder, with maximum dimension 800 in height and width, 300dpi, at 95 quality.
I also set sharpening for screen "Standard" level in Lightroom 2.2 (wasn't in v.1).

Then if the file is larger than the 293K limit, I use Thumbs+ to run one pass of unsharp mask and then save - then tweak the size for as near as 293K as possible.

I don't remove the EXIF information, I actually add the Lightroom hierarchy to the image as well. To get a slight reduction in size, I use the Interleaved option - but it's not usually worth it.

Quote:

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Originally Posted by A.M.D.A.

I see many PR members post photos in the forums at 800x600 pixels, with file size under 293.0KB. Yet the shots look very good, detail-rich and with no hint of JPG compression or pixelating. I, however, struggle to keep 600x400 pixel shots under 300KB!

What is your preferred method for reducing file size – and why. Here are some I can think up of, I often apply all of them:

• JPG compressing.
• Chroma subsampling.
• Stripping EXIF data.
• Deleting thumbnail.
• Resizing further.

Also are there any "tricks" for obtaining best possible image quality?

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I'm using PS Elements. I just use the Image>Resize>Image Size and set the longest side to 800. Sharpen for the first time. I then Save As... a jpg and a box comes up where I set the Quality. As I change the Quality it shows the file size so I choose the best Quality under 293 KB (for this site). Done. EXIF is still there. Elements also has a 'Save for Web', but it strips the EXIF data. - TF

I use a similar method as SmartWombat in PSP it gives a preview of image quality as you adjust the compression of the export so you can immediately see how compression will effect image quality. FWIW I didn't need to start doing this until I started using ACDSee to do the RAW conversions, the Fuji hyper utility always yielded JPGs well under the limit. But comparatively speaking, hyper utility SUX compared to ACDSee. MUCH happier w/ the new software.

I normally compress with Corel PhotoPaint at between 7 and 10 percent, which is very difficult to see. That amt almost always keeps me below PR's 293k limit, unless there is an incredible amt of detail or colors in the shot. I really start to notice if I set my compression to 15-20% or higher.

G

Thanks very much for the replies and suggestions, everyone ! :)

So I'm trying to buy the right software that will help me to convert a huge file into the size prints I want. How do you guys do this? Say for instance I'm using a 21.1 mp camera. We know the file is going to be HUGE. How do most of you go about getting your prints. Save it to an SD card..? And take it to a photo shop? Do you have to resize first? If so how do you do it and using what program.

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Originally Posted by Lynnzora

So I'm trying to buy the right software that will help me to convert a huge file into the size prints I want. How do you guys do this? Say for instance I'm using a 21.1 mp camera. We know the file is going to be HUGE. How do most of you go about getting your prints. Save it to an SD card..? And take it to a photo shop? Do you have to resize first? If so how do you do it and using what program.

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Those are a lot of questions.

Actually, you don't need to resize/crop photos before sending them out to be printed. The only thing that will happen is that your prints may come out with "hands missing", "heads chopped off", or pixelated. So yes, I'd suggest to carefully prepare the photos. I am employing GIMP 2.6, but there are lots of other programs which will work.

#1. Open the file and perform basic edits, such as brightness, contrast, saturation, color, cloning, sharpening, etc.. But don't crop – yet.

#2. Select the crop tool and type in the aspect ratio of the print size you are going to do. For example, a 4x6 inch print has an aspect ratio of 3:2, type this in and select "fixed aspect ratio", so it stays constant as you adjust the crop box. Note the pixel size of the cropped image, if it is too small you may not get satisfactory prints.

Attachment 63686

#3. Open the "Print size" window. You will now see the total pixel dimensions of your image, and the pixels-per-inch (ppi). Usually the camera-default ppi is 72, you have to change to a minimum of 200, 300 is considered optimal. Of course you can go to 400 or 500.

Attachment 63683

If the ppi is ridiculously large, try using the "Scale" tool, which simply throws away unneeded pixels. Scale bit-by-bit and then try "Print size" again.

Attachment 63684

Now the finished/saved file is to be printed. If you have already decided on which shop to use, you can either take the photo/s in on a SD card, CF card, CD, flash memory drive, etc., depending on the particular shop. I prefer to send my photos in through their special website and then I get notified by email or phone when the prints are ready to be picked up.

Nice explanation there Alex!

Thanks GB1, I am glad to help. :)

I always use the PicSizer to Reduce and optimize the size of your photos easily, its best for editing cropping and for resizing an image. It is very easy to use,even very beginner can have fun with it.

Thanks benlinus, I have use I used PicSizer for the first time. It is very user friendly and easy to use.