Longshadow Loc: Audubon, PA, United States

I found another interesting fact about the thumbnail images at UHH. In addition to them usually being smaller than what is uploaded, and the color space may be different than the original, all appear to be converted to JPEGs (except if the original is a JPEG) for the thumbnail, no matter what you upload.

Preface: When I publish images on my website, they stay what they are originally. If I upload a GIF, it remains a GIF. I thought this was the norm. Since I post JPEGs here, I didn't know about (and never expected) the conversion until I had a dialog with rehess on a thread about Round Images and did some further investigation.

He stated that the image he posted had the round image, a white background, and a transparent area. Since I thought the thumbnail was simply a smaller version of the uploaded image, I had no need to look at the uploaded image (download). All I could see (in the thumbnail) was the image and a white background. I was very confused.

Since when I publish an image on my site, any transparency will show the background color for the page. In a table, the background color for a cell can be set with the bgcolor="<color>" attribute. When I went to look at the source code for the image download option, I was looking for a bgcolor="white" attribute.
What I found was no code for the page, just the image, and the image was a PNG. With the circle image, the white background for the square around the circle image, and two light gray areas on the sides, representative of transparency. Dang.

You can see that this is true by looking at the images I posted, then looking at the download of them.
Since JPEGs do not support transparency, you get a white background for the transparent area.

The light gray areas exist in GIF and PNG images because the canvas size for the original image before the circle crop was not reduced to the size of the crop. So it has to be "something". If one uses the original canvas size, the area the image covers cannot be reduced, even though the crop is smaller.

It turns out that with an uploaded JPEG, there is no difference. But if you upload a GIF or a PNG, when the thumbnail is created, the image is converted to a JPEG for the thumbnail. I did not anticipate that. I have no idea if other image formats are also converted. I deal with JPEGs for display 99.9% of the time.

So both rehess and I were correct for what we were each referencing. We each were just referencing two different images. He was referencing the PNG he upload, and I was referencing the JPEG thumbnail I was viewing.

Surprise, surprise, ya learn something new every day.

Thanks rehess!

rehess Loc: South Bend, Indiana, USA

I started off with limited knowledge about “transparency” and no knowledge about what “round crop” means in a practical manner. From my use of language you may see my learning as we stepped through that thread, so we both benefitted.

Thank you

Longshadow Loc: Audubon, PA, United States