JPEGCrops FAQ

The blowing wind

JPEGCrops questions

Q: Why would I want to crop my images?

Most digital cameras produce JPEGs with the aspect 4:3. A very common papersize for photo albums is 4"x6" (10x15cm), which has the aspect 3:2. If you want to print, you often need to crop.

Q: Why can't I just use PhotoShop?

You can use PhotoShop, Gimp, PaintShop Pro, PhotoFiltre or whatever program you fancy for cropping. If your normal workflow includes sharpening, fiddling with color levels and so on, it will probably be easier to incorporate cropping than switching to JPEGCrops.

If you just want to crop a lot of images, JPEGCrops will most probably be a lot faster and easier than the mentioned programs.

Q: What does lossless mean?

The JPEG format is lossy. That means that information is lost when an image is packed as a JPEG, artefacts are introduced. How much is lost depends on the quality selected. Opening a JPEG, manipulating it and saving it as a JPEG again normally means that the artefacts accumulate. How much depends on the image and the program.

JPEGCrops avoids this degradation by using JPEGTran which doesn't repack the JPEGs: It merely throws away some of the data and keeps the rest unchanged.

One could argue that it would be better to avoid JPEGs in the first place, but most online print services (at least in Denmark) will only take JPEGs.

Q: Can't I just save as JPEG 100%?

JPEGs saved at 100% quality does not mean that all information is preserved. 100% is just the end of a widely used scale. Check the JPEG-FAQ for details about this.

Q: Can I crop as I like?

The lossless rotation only works when the width and the height of the image can be divided by 16. Actually that's sometimes 8, but I haven't found the time to make a check for that. The lossless cropping has similar requirements for the upper left corner of the cropping area.

Q: Why can't I hit the bottom or right side?

See the question above: The upper left corner of the crop area needs to be aligned to a 16x16 pixel grid. Try resizing the area instead.

Q: Can I trust the sizes?

Yes and no. The different sizes should be pixelprecise to what you'd get if you calculated them yourself, but most online printers cut a little bit of the edges of the paper. How much they cut depends on the hardware they use, so it's probably wise not to crop too closely.

Another thing to remember is that most metric specifications for paper is only approximations. When a company says that their paper is 10x15cm, they probably mean 10.16x15.24cm.

Q: What's this about 10x15cm?

JPEGCrops comes with a list of predefined paper sizes. Some people are confused that the 10x15cm size in JPEGCrops is really 10.16x15.24cm. The 10x15cm that users of the metric system are used to is rounded from inches. Take a ruler and try to measure your 10x15cm photo. You'll probably see that the photo is a little bit bigger than expected.

A 10x15cm photo is really a 4"x6" photo. An inch is 2.54cms, so a 4"x6" photo is 4*2.54x6*2.54cm = 10.16x15.24cm.

Q: How many PPI?

That depends on the printer, the papersize and your eyes. The default quality indicators (<150 PPI = low, 150-299 = medium, >=300 = high) are very conservative. Personally I can't tell the difference between 250 PPI and 300 PPI for photos.

For posters or other large prints, chances are they will be viewed at a distance. That lowers the PPI requirement.

Q: What's the guides about?

JPEGCrops can overlay the crop area with guides using the Rule of Thirds or a simplified Golden Section. The giudes are supposed to make it easier to select a generally pleasing composition.

Q: Can JPEGCrops destroy my images?

The actual image manipulations are performed by JPEGTran and unless you choose otherwise, the original files will stay untouched, so you should be pretty safe from catastrophes.

Q: Why is JPEGCrops beta?

Because it's not finished yet? Fear not, I never seem to be satisfied enough with my programs to promote them to version 1.0. There were some rough times before version 0.5.18 beta, JPEGCrops has been pretty stable since then.

Q: Is this a popular program?

JPEGCrops has been on CDs for both a german and a polish computer magazine, so I have no idea about the number of people who has tried it. If you want, you can take a look at the download statistics.

Q: Why don't you answer email?

I do, but sometimes it takes months. JPEGCrops is a project that I work on when I find the time. Depending on the content of the email you send, I might find that I don't have the energy to answer it at once.

Q: Could you please add feature X?

Maybe. Go to the feedback page and put your suggestion there. The same goes for bugreports. Please read the future page first, in order to avoid duplicate requests.

Q: What about an OS X version?

A few people has asked if JPEGCrops run or will run on MacOS or OS X. I'm sorry to say no. It cannot and probably never will. I recommend taking a look at the list at About.com instead.

Q: What about a Linux version?

While JPEGCrops does not run natively under Linux, it runs just fine under Wine.

Q:Why won't my program open a cropped JPEG?

Certain cropped JPEGs won't work with certain programs (MS Paint for instance). The solution is to turn off Update PPI on crop under Visual in the preferences.

Q:Can JPEGCrops resize images?

Yes and no. It is possible to call arbitrary programs upon cropping, so with a little work, JPEGCrops can be persuaded to do a lot of things. Take a look at the scripting guide.

Q:Does JPEGCrops run under Vista?

I haven't tried it myself, but other people says yes. Some say that it requires administrator privileges, which I suspect is due to use of the file JPEGCrops.ini that resides in the installation directory. Choosing "Use individual settings for each user" at install time might remedy this, at the location of the JPEGCrops.ini will then be changed to the user folder..

Q:Why don't you answer your emails about JPEGCrops?

Ouch. You're right. I am a bastard. I have no good answer to that question. I hope that some day I'll butch up at be active in that area again.

Q: Who are you?

I am a computer scientist from DAIMI. I live in Denmark and have a girlfriend, a daughter, a son and a full-time job. Performing a search on Google for my name should give you all the information you never wanted. As far as I know, I'm the only "Toke Eskildsen" in existence.

Q: Can I have your babies?

No. My girlfriend would be upset. Besides, I kinda like them myself.