How to maintaining JPEG file size when "Save As"

[chrislawson]

After making corrections to a photo I do a save as and the file size goes from 2m to 500k. How do I prevent that?

[LeviFiction]

Run the JPEG optimizer. It allows you to set the default settings for saving a JPEG file. You'll want to increase the slider to best quality. Right now it's probably set to average quality and average file-size.

You can access this from the save dialoge, should be one of the buttons, or from the File menu. Go to File->Export->JPEG Optmizer.

That should help.

[df]

If you want to have Save As do the same thing, click the Options button at the bottom of the Save As screen and set the compression factor down to 1.
You may also want to set to Standard Encoding, Save Exif Data, Chroma Subsampling: none, Embed ICC Profile. Then again you may not on some of those.

[Tim Morrison]

A couple of other points...
If you're doing much editing of a particular image, don't save it as a JPEG. JPEG is a format that uses lossy compression to reduce file size. Multiple resaves of a JPEG will cause a loss of image information. The best workflow is to open your original image, press Shift + D to duplicate it, then close the original. Edit the duplicate and save it in a lossless format such as PSPIMAGE, PNG or TIF. Only PSPIMAGE will preserve everything that can possibly be done in PSP, but TIF or PNG are more likely to be understood by other software. Only make a JPEG copy of the final edited file if you really need a JPEG for some reason.
Secondly, the file size of a JPEG is only a very approximate indicator of image quality. As a example, open one of your original JPEGs, press shift + D three times to make three duplicate copies and then close the original. Take note of the file size of the original.
Go to the JPG Optimizer (File > Export > JPEG Optimizer). Notice that the right-hand sample image has the size of the compressed (i.e. saved) image under it. Adjust the compression value until that compressed size matches the size of your original image as closely as possible. Save it with a filename like "original.jpg", then close the duplicate copy (without saving further).
For the next copy go to Adjust > Softness > Soften, the save using he JPG Optimizer with the same compression value as before. Note that the file size is smaller.
For the final duplicate go to Adjust > Sharpness > High Pass Sharpen, then save that image in the same way.
Notice that the softer image has a smaller file size and the sharpened image has a larger file size.
In general sharper, more detailed or noisier images will produce larger file sizes than softer, less detailed images when saved with the same level of JPG compression.
You'll also find that, despite it's smaller file size,if you save a copy using PSP's default settings, it will look virtually the same as the original.

[chrislawson]

Thanks guys - One learns something everyday - Much appreciated the solution and the education and the challenges with Jpeg files