PNG | Blog | Iminify

Bar chart of the resized files WordPress 7.1.2 made on the server and in Chrome: 691 and 640 KB for a 1800 px photo, 1,942 and 2,193 KB for its 6000 px version, 553 and 651 KB for a PNG screenshot.

JPEG
PNG

Does WordPress compress images? What WordPress 7.1 does to your upload

We uploaded the same photo to a fresh WordPress 7.1.2 site twice, both times from Chrome. The file we sent, 832 KB, was stored byte for byte both times. From it WordPress made five resized copies at JPEG quality 82. Through Media > Add Media File those copies came to 691 KB. Through the Upload button on an Image block they came to 640 KB, because in 7.1 that button has the browser make the copies instead of the server. So does WordPress compress images automatically? Not the file you upload, which is stored byte for byte. It re-encodes the resized copies it makes, the JPEG ones at quality 82. In our test a phone and a standard laptop screen downloaded copies of this photo, but a 2x laptop screen got the untouched original, so compressing it is still your job. Since 7.1, which program makes the copies depends on the button you press and the browser you press it in.

Oct 5, 2026 8 min read

ComfyUI's Flux Dev example render of a fox-eared girl in a maid dress holding a cake, captioned: 1,215,064-byte PNG to 125,684-byte WebP, and the workflow still loads in ComfyUI.

ComfyUI PNG to JPG loses the workflow. WebP and AVIF can keep it

ComfyUI's Flux Dev example image is a PNG of 1,215,064 bytes, and the two text chunks holding its prompt and workflow take 12,240 of them. The rest is 1024x1024 pixels stored without loss. Across the 92 PNGs in ComfyUI's examples repository that carry a workflow, the text was no more than 3.32 percent of any file, with a median of 0.62 percent. Converting to JPG shrinks the file, but ComfyUI's own loader can't read a workflow back out of a JPG. A WebP or AVIF can keep it, at about a tenth of the size. We took the text-to-image examples of ten models from ComfyUI's examples repository, made smaller copies several ways, and dropped the copies back onto ComfyUI 0.37.0's canvas to see which ones still held the workflow.

Oct 3, 2026 6 min read

The fjord photograph from our test set above two bars: 3.07 MB as a PNG and 555 KB as a JPEG at quality 90.

JPEG
PNG

Why is my PNG file so large? Four causes, measured

We took the fjord photograph from our test images, a 1,800 by 1,200 JPEG of 832 KB, and saved the same pixels as a PNG. It came to 3.34 MB at the default setting of Pillow, the Python imaging library. Through zopflipng, a slower lossless compressor, 3.07 MB. As a JPEG at quality 90 it's 555 KB, and it scores 84.22 on a perceptual scale where 80 means an average observer can't see the difference side by side. A photograph was the most expensive of the four causes in the comparisons below. The four: It's a photograph. It has more pixels than it will be shown at. It stores more per pixel than the picture needs: 16 bits per colour channel, or millions of colours where 256 would do. The program that saved it didn't compress it very hard. Each has its own fix, and the fix for one can be wrong for another. A JPEG rescues a photograph. Our desktop screenshot came out bigger as a JPEG than as a PNG through zopflipng.

Sep 28, 2026 7 min read

Bar chart: a 12.5 MP phone photo at JPEG quality 90 is 4,309,090 bytes as a file and 5,745,456 bytes as base64, past a dashed line at the 5,242,880-byte limit on Bedrock and Google Cloud.

Image exceeds 5 MB maximum? Claude counts the base64, not your file

Our 12.5-megapixel test photo, re-saved with jpegli at quality 90, is 4,309,090 bytes. That's under 5 MB, and it's still too big for Claude on Amazon Bedrock or Google Cloud. Anthropic's limit there is "5 MB (base64-encoded)", and base64 turns those 4,309,090 bytes into 5,745,456. The error compares the encoded size with 5,242,880 bytes, as in this one from a Claude Code issue: image exceeds 5 MB maximum: 5281812 bytes > 5242880 bytes. So the ceiling is 3,932,160 bytes of actual file on Bedrock and Google Cloud, and roughly 7.5 MB on the direct Claude API, whose limit is 10 MB. Separately, no side may pass 8000 pixels, or 2000 once a request carries more than 20 images. For photos, one step clears all of it: resize to 2000 pixels on the long edge and save it as JPEG.

Sep 27, 2026 8 min read

The same app icon twice: as a 19,794-byte WebP with its transparency showing the background through, and as a 63,801-byte JPEG sitting on a white square.

WebP
PNG

Does converting PNG to WebP lose quality? Five files, every pixel checked

We converted five PNG files to WebP with the encoder forbidden to throw anything away, then compared every pixel against the original. All five kept every 8-bit pixel, and the files were between 28.6% and 77.3% smaller. So no, converting a PNG to WebP doesn't have to cost you anything you can see. The catch is that it isn't the conversion you're usually pointed at. Of the first four results for this question in September 2026, three recommend a quality number between 80 and 100, and in cwebp every one of those is a lossy setting. So is the button marked "compress PNG". Here's what each of them actually costs.

Sep 25, 2026 8 min read

Bar chart of ten test images: each one as AVIF, sized against the same image as WebP at a matched quality score. The bars run from 29.8% on the transparent icon to 74.5% on the product photo.

AVIF vs WebP file size: ten images, one quality score, and where WebP still wins

Five of the fifteen pages we read for "avif vs webp file size" put AVIF 20 to 30% under WebP, ShortPixel among them. Six give no comparable figure, three put it between 11.76% and 50%, and one forum thread reports an AVIF twice the size. We put the ten images of our published corpus through cwebp and two builds of avifenc, bisecting each to the same SSIMULACRA 2 score of 80. The totals: 1,675.4 KB for WebP, 1,114.7 KB for a current AVIF, 33.5% smaller. So the headline is roughly right. It's also the least useful number here. If the verdict is all you want: AVIF for photographs and screenshots, WebP for lossless, and WebP again on our one transparent image once both encoders keep the alpha plane lossless.

Sep 23, 2026 8 min read

Bar chart: one 832 KB photo through jpegli costs 159 KB at a SSIMULACRA 2 score of 50, 311 KB at 70, 473 KB at 80 and 847 KB at 90.

SSIMULACRA 2 scores in practice: what 50, 70 and 90 cost in kilobytes

We ran cwebp at quality 75 over ten images, at the settings below. A night skyline came out at 63.0 on the SSIMULACRA 2 scale, an app icon at 83.1. Same encoder, same quality number, twenty points apart, and 63 sits below the line the scale calls "artifacts are perceptible, but not annoying". A quality number tells the encoder how hard to try. SSIMULACRA 2 describes what came out, on a scale topping out at 100, and means much the same for a JPEG, a WebP or an AVIF. So we measured what each point costs: ten public images, three encoders, a grid of quality settings across each encoder's range, bisected around each target.

Sep 20, 2026 8 min read

Two cards next to the command avifenc -s 6 -q 60 -y 444: libavif 1.2.1 writes 38.5 KB at SSIMULACRA 2 68.2, libavif 1.4.2 writes 76.6 KB at 76.2.

What AVIF quality setting should you use? The answer changed in March 2026

We ran one avifenc command on one photo, the raspberries from our corpus, in two containers. On Debian 13, whose libavif-bin is 1.2.1, it wrote 38.5 KB. On Alpine edge, which packages libavif 1.4.2, it wrote 76.6 KB: twice the file, the biggest increase of our ten, at a SSIMULACRA 2 score of 76.2 instead of 68.2. Neither container is broken. In March 2026 libavif changed what the number means.

Sep 18, 2026 7 min read

Try it on your own images