Convexy

How to convert PDF to JPG on iPhone

This renders the PDF's page into a photograph-style image — useful when you need a picture of a document rather than the document itself. There is one limitation you need to know before you start, so let's lead with it.

Convexy converts the first page of the PDF only. A JPG is a single image; a PDF may have two hundred pages. Rather than silently picking one for you and hoping, here is the rule stated plainly: you get page 1. To convert a different page, use the free PDF Split tool under Tools to extract that page into its own PDF first, then convert that.

What rendering actually means

A PDF page is a set of drawing instructions — vectors, embedded fonts, and images. It has no fixed pixel size; it can be printed at any resolution and stay sharp. A JPG is a fixed grid of pixels. So this conversion is a rasterisation: the page is drawn at a chosen resolution and frozen into a bitmap.

That means you must pick a resolution, and Convexy exposes that choice directly. The PDF quality setting in Options maps to real dpi values:

Once rasterised, that resolution is permanent. Choosing 72 dpi and enlarging the JPG later gives you a blurry mess — the detail was never captured.

Text becomes pixels

The single most important consequence: the text stops being text. A PDF's text layer is searchable, selectable and copyable. A JPG's is not — it is a picture of letters. If what you actually want is the words, do not convert to JPG. Convexy can convert a PDF directly to TXT, which pulls the real text layer out and gives you characters you can search and edit.

Choose JPG when you want a picture: a preview thumbnail, an image to post or message, a page to drop into a slide deck, something to hand to a system that only accepts images.

JPG is a poor fit for text-heavy pages. JPEG compression puts ringing and mosquito noise around exactly the sharp, high-contrast edges that letters are made of. For a page of text or line art, convert to PNG instead — it is lossless, and the glyphs stay clean. Use JPG when the page is mostly photographic, or when the file must be small and a bit of fuzz is acceptable.

Transparency and background

The page is rendered onto a white background before being encoded. PDFs with transparent or unpainted regions will show white there, which is almost always what you want for a document and is worth knowing if you expected otherwise. JPG has no alpha channel in any case — it could not preserve transparency even if the page had it.

It happens on the device

PDFs are the most sensitive category of file most people own: contracts, statements, tax returns, medical letters, legal correspondence. Uploading one to a free web converter to get a JPG back is a genuinely bad trade.

Convexy renders the page with Apple's PDFKit, locally. No server, no account, no upload, no network request. It works in Airplane Mode, which is the easiest way to confirm the claim rather than take it on faith.

How to do it

  1. Extract the page you want first (if it isn't page 1)

    Open Tools, choose PDF Split, and pull the page you need out into its own PDF. Skip this step if you want the first page. PDF Split is free and never gated.

  2. Bring the PDF in

    Tap Browse files and select the PDF, or share it into Convexy from Mail, Files or another app.

  3. Choose JPG

    Convexy offers the formats a PDF can become — JPG, PNG, TIFF or TXT. Tap JPG. If it is the text you are after, pick TXT instead.

  4. Set the resolution

    In Options, choose Screen (72 dpi), Standard (150 dpi) or High (300 dpi). Pick High if the image will be printed or zoomed; the rasterised resolution cannot be increased afterwards.

  5. Convert, then save or share

    You get a JPG of the page rendered on a white background. Save it to Photos or Files, rename it, or share it on.

Common questions

How do I convert every page of a PDF to images?

Convexy converts the first page of a PDF to an image. To get another page, use the free PDF Split tool to extract it into its own PDF, then convert that. For a whole document, split it into single-page PDFs and batch-convert them. It is more steps than a tool that claims to do it in one, but it is what the app actually does, and the page you get is never a surprise.

What resolution should I choose?

Standard (150 dpi) for anything you will look at on screen. High (300 dpi) if the image will be printed, zoomed into, or if the page has small text you need to stay legible. Screen (72 dpi) only for thumbnails. Rasterisation is one-way — you cannot add resolution back later, so err high if you are unsure.

Can I still search the text after converting to JPG?

No. Rasterising turns the text layer into pixels — the characters no longer exist as characters. If you want searchable, selectable, copyable text, convert the PDF to TXT instead; Convexy extracts the real text layer rather than making a picture of it.

Should I convert a PDF to JPG or PNG?

PNG for text, tables, charts and line art — it is lossless, so glyph edges stay clean. JPG for pages that are mostly photographic, or when the file must be small. JPEG compression damages exactly the high-contrast edges that text is made of, so a text page rendered to JPG often looks visibly fuzzy around the letters.

Why is my JPG blurry?

Almost always because it was rendered at too low a resolution. A PDF page has no inherent pixel size — it is drawn at whatever dpi you ask for. At Screen (72 dpi) a dense page of text will look soft, and enlarging the JPG afterwards cannot recover detail that was never rendered. Convert again at High (300 dpi). The other possibility is that the PDF itself contains a low-resolution scanned image, in which case no setting will help.

Is my PDF uploaded to a server?

No. Convexy renders the page locally with Apple's PDFKit — there is no backend, no account and no network call involved in a conversion. Given that PDFs are usually contracts, statements and medical letters, this is the whole reason the app exists.